Love, a widely discussed topic in literature and art for centuries, has also become an interesting theme in psychology, as it is considered an important emotion in the life of a human being. It stimulates people, even in cultures beyond the Western world, to commit to lasting relationships, such as marriage or cohabitation , and this has relevant repercussions on the life and evolution of men and women, who thus ensure a necessary rearing for children and develop their social intelligence and cooperative skills .
Love is a feeling that is especially expressed by the people involved in romantic relationships and is considered, along with a number of other factors (such as intimacy, commitment, and affection), one of the most significant components for a satisfying relationship  and for its duration . These are aspects that, within the wider scope of relationship quality, are related to subjective well-being, especially in terms of happiness, life satisfaction, and the existence of more positive past experiences as opposed to negative feelings  .
On the other hand, love relationships can also be a source of stress, discomfort, struggle, pain, and negative feelings, especially when associated with dependence and obsessive behaviour, which may negatively affect the quality and duration of a relationship   . In certain cases, it is recorded how love may also be translated to pathological love (PL) that, although not diagnostically referred to as a clinical disorder, is assimilated in research―even neurophysiology research―to psychopathologies related to substance and behavioural addictions .
This expression of love in its healthy and pathological connotation   already hints the polysemy of the feeling, which is in any case confirmed by numerous studies that point out the various ways and peculiarities of living and expressing it in different relationship types (friendly, romantic, parental, etc.) and within the same romantic relationship  .
Throughout the years, different classifications of love have been hypothesized and are widely present in empirical literature as important points of reference for the development of psychological knowledge in the field. Berscheid and Walster  proposed an initial distinction between passionate love―an intense emotion distinguished by a strong desire to bond with one’s partner―and companionate love, which implies feelings such as affection and tenderness. In literature, we may also find another kind of love, called compassionate love (CL), a feeling oriented towards care, help, and worrying for another, who may even be a partner in a romantic relationship, especially if suffering and needy . Considering the different attitudes people have towards romantic love, Lee  has identified and coded six love styles: three are primary and three are secondary. Primary styles include Eros (passionate, romantic love), Ludus (playful love), and Storge (friendly love). Styles considered secondary, being combinations of two primary styles, include: Mania (obsessive or addictive love), a combination of Eros and Ludus; Pragma (practical, rational love), a combination of Storge and Ludus; and Agape (altruistic/unselfish love), including Eros and Storge (in Table 1, we present a brief description of the main characteristics of each love style). It is one of the most utilized classifications of love, and also the most structured, complete, and focused on romantic relationships. It is no coincidence that it was the basis for the development of a tool called the Love Attitude Scale (LAS) , which measures the six love styles and is commonly used in research. It has also been adjusted to different countries―including Italy  ―as a proof of its reliability and validity.
Table 1. Brief description of love styles.
Some of the components of the six love styles seem to have common traits with those used in other classifications , which nonetheless appear more general and less specific to love relationships. For instance, the altruistic attitude of the Agape love style is comparable to the compassionate love type, although the former focuses on romantic relationships, whilst the latter is conceived as a love type that may be experimented to achieve a wide range of goals, including relationships with a partner, but also with friends, family, strangers, or even humanity as a whole . Neto  recorded that compassionate love may be correlated to four of the six love styles: positively with Eros and Agape, and negatively with Ludus and Pragma, while he found no link to Storge and Mania. Passionate love has been identified by Acevedo and Aron  as a combined measure of romantic love and obsession, and Graham  observed how it shows a correlation to Eros or Mania.
In order to understand if and how the various love styles may explain a possible variability in a love relationship and its quality―even with respect to personal and relational well-being―we here present a literature review that may help understand what empirical studies have focused on the subject matter. Such review may be useful in defining further outlets in research and in assessment and preventive praxes related to the health and well-being of partners in a relationship. In fact, acknowledging how―and on which levels―the different styles can influence the relationship both as risk factors and as resources may help target the prevention operation towards crucial details to act on in order to promote an improved relational quality.
To identify and assess the articles relevant to the review, the research group devised some inclusion/exclusion criteria to choose papers relevant for this review. These criteria regard: publications in peer review journals; focus on love styles distinguished by Lee and exclusion of papers that focused on other love taxonomies; focus on both marital quality/stability and relational dimensions; good quality of the research method and its accurate description in the paper.
In order to identify the studies and research projects relevant to this review, we have used electronic databases such as ScienceDirect, PsycINFO, PubMed, Scopus, and Google Scholar. The most part of the papers were collected from Google Scholar and ScienceDirect. We have considered papers in English and Italian published from 2004 to this day, implementing the meta-analysis proposed by Masuda  as a means of synthesis of the research results. Masuda studied the correlation between relational satisfaction and two love types―passionate and companionate―measured by means of various tools applied to the most widespread theories. It was thus a more limited review―in terms of the variables considered―compared to the one presented in this article, but that in any case offered a framework of the state-of-the-art up until the date of its publication, and which supported the difference between Lee’s theory and other theoretical models of love, giving credit to the greater elaboration of the former.
The following key words and key word combinations have been used for this review: love or love style and marital quality, marital stability, marital satisfaction, marital well-being and health.
2.2. Inclusion/Exclusion Criteria
We have included studies and research projects published from 2004 to 2018 that analyse the love style topic, along with variables in the quality and duration of the relationship. We have excluded the ones that did not involve love styles and relational aspects in their analysis. In any case, in drafting our introduction and discussion/conclusions we have also referenced articles analysing the theme of love and its classifications in terms of personal, social, and even health and well-being characteristics.
Given that our aim is to provide an initial review of scientific literature on the influence of different love styles on the quality and duration of the relationship between two people, the research was limited to articles of a high methodological quality. We have in any case considered complete projects published in peer-review journals, and have excluded summaries presented at seminars, reports introduced at conferences, dissertations, and comment articles that provided only partial data and authors’ opinions. We also excluded the articles we have not managed to retrieve, even upon direct request to the authors by e-mail.
2.3. Screening and Material Selection
The articles retrieved have been assessed by two independent reviewers. They were first selected based upon their title and abstract: 1943 articles to be potentially included in this review were identified on this basis. This initial screening also included papers dealing with love, love types, and love styles, even when not assessing the effects on the quality and duration of the love relationship. Upon a second selection based upon the titles and abstracts, we identified 235 articles concerning the general topic (love, love types, love styles) and retrieved their full text. We added a further 60 articles to these, and two reviewers have selected the abstract pool on the basis of the relevance of the topic dealt with to this review, and their methodological quality. This process has narrowed the pool to 122 articles. We successively focused only on those that concerned love styles in relation to quality and duration aspects in the love relationship, and for the purposes of the analysis we identified a sample of 22 articles (Figure 1).
Each of the 22 articles was analysed in depth, in an attempt to identify the theoretical basis, the goal and hypotheses, the research design, the procedure and tools utilized, as well as the main results recorded, using a specific, detailed method. In terms of systems and literature research, we have assessed the objectives, methods, and results obtained. As for the results, every publication has been summarized and classified in accordance with the six love styles described in Lee’s theory of love . The method has been deemed by the researchers the most straightforward for a facilitated recognition of the effects of each love style on relational health and well-being. Throughout such phase, some doubts and perplexities about the inclusion of papers and their methodological quality were discussed between the two researchers, occasionally through the involvement of a third researcher.
Figure 1. Search and screening papers.
The 22 articles considered in the scope of the review were all published on peer-review international journals; they are for the most part empirical researches, and three meta-analyses were also consulted. An article by Acevedo and Aron  includes, along with a meta-analysis, even a literature review that we have not considered in our assessment, in that it deals with a more general topic than the one in concern. The articles focus on the correlation between and influence of the various love styles on the different variables affecting relational quality, some of which are considered in the same research design. Depending on the situations, the relational dimensions are analysed in combination with different variables (also regarding―along with socio-personal and cultural characteristics―well-being, health, psychopathology and family history), and love styles are considered mediation variables. While generally the effects of love styles on marital quality and stability are analyzed using an individual approach, Gana et al.  adopted a dyadic approach and the Actor-Partner Interdependence Model. This choice permitted them to know not only how the love style of one member affect his/her marital quality perception (actor effect), but also the partner’s one.
A widely shared denominator or precondition to the goals formulated in the different research projects analysed in our review is the centrality of love in the construction and maintenance of relational quality, which is often linked to theories of love and relationships. An additional recurring common denominator in the assessed papers is the recording of both the contradiction between studies on love and the lack of knowledge on relevant topics.
3.1. Methodological Characteristics of the Reviewed Research Papers
In terms of methodological characteristics, we shall make a distinction between reviews and empirical research, in that we have adopted different method assessment criteria for each. For the reviews, we have identified the type, inclusion/exclusion criteria, the number of studies considered by the authors, and the reference population. As for the empirical research projects, we have assessed the method on the basis of the characteristics and origin of the sample, the type of sample, the setting, the procedure, the independent and dependent variables, and the tools used. We have identified two reviews, one by Acevedo and Aron  and one by Graham , both conducting a meta-analysis of the research projects assessed. Acevedo and Aron  conducted a meta-analysis of 25 researches and studies satisfying specific inclusion/exclusion criteria, including: duration of the relationship; focus on relational satisfaction (dependent variable) and love styles; romantic, obsessive, and companionate love; dimensions such as passion and intimacy (independent variables). Graham  selected 81 studies, which were required to: be in English; use a data collection method based on at least one of the measurements of love most utilized in literature (independent variables); and identify correlations between such metrics and relational variables, such as satisfaction and duration (dependent variables). Graham applied an inter-metric model of correlation that allowed to record common characteristics. Most of the 22 research papers apply a cross-sectional design and a quantitative approach. The research projects have been conducted in various different countries and cultures, and especially involved the white-Caucasian ethnic group or, in some cases, other ethnicities but as a minor percentage of the sample   . The only exception was the sample considered in the research by Smith and Klases , including 56 participants from the UK (London) and 52 from Hong Kong. Moreover, we found two studies focused on the Islamic population   and others presenting a comparison between different cultures  .
The sample size ranged from 12 to 1582 participants. The latter were mostly single university students, though certain researches included married individuals   or individuals in a committed love relationship   . The only two studies that considered (heterosexual) couples as well as the percentage of couples with children are that carried out by Gana et al.  and Vedes et al. . Certain studies   have considered clinical samples (patients suffering pathological love and jealousy), or partners that have experienced special situations such as cheating . The samples included both females and males; only Honari and Saremi  have taken into consideration a female-only pool. The average age varied and the age range in most cases was quite broad. For example, in the research conducted by Lin & Huddleston-Casas  the range was 19 to 91 years. Where specified, participants mostly belonged to the middle class  .
Sampling was generally performed on a voluntary basis, though some authors used random sampling  . Although most studies involved persons attending academic institutions such as universities, in certain cases participants were involved by means of advertisement, postings, e-mail, and other methods    .
Generally speaking, consent to take part in the research was requested to participants, while in certain studies it was also obtained from the institutions  .
Most of the research projects used standardized instruments, at times translated in the language spoken in the country where the research was conducted, then validated  and administered individually. In measuring love styles, a broadly used metric is the Love Attitudes Scale Short-Form (LAS-SF) . Certain studies also adopt measurements designed ad hoc, especially for the assessment of relational dimensions , and a single study used the phone interview method . The most important information about these aspects are synthetized in Table 2.
3.2. Summary of Data Present in the Research Projects Reviewed
We have classified the results extrapolated from the researches in accordance with the six love styles identified by Lee . This approach allowed us to organize content in relation to the correlations and influence that the different love styles may have on the health and well-being of a love relationship. At the same time, it allowed us to quote the reviewed articles more than once in case they dealt with more than one love style.
Table 2. Topic, objectives and methodological characteristics of the reviewed research projects.
Eros love style and its relational correlates
This style expresses romantic love―distinguished by passion as well as physical and emotional attraction―is widely correlated to a high intensity of the love feeling, quality of life, and subjective well-being , as well as healthy love , and the various works analysed appear to confirm its positive value. In fact, it appears to be related to the good qualities of a relationship and of married life , as well as dyadic satisfaction     . The positive correlations are stable and do not change over time, in that they exist both in short and long-term relationships   and in all age groups , nor do they mutate in different cultures, as recorded by Galinha et al.  who made a comparison between Americans, Mozambicans, and Europeans (Portugal). The positivity of the Eros love style is further attested by the results of researches that have proven its direct associations with specific dimensions, such as attachment security , the desire for intimate closeness to the partner , positive strategies for conflict resolution such as compromise , and dyadic coping, namely the joint effort by both partners to face a stressful situation lived by one of the two . Besides, this love style is correlated to commitment in a relationship  expressed by a couple, which has expectations in terms of its duration, coherently with a romantic conception of love, as proved by the presence of negative emotions upon conclusion of the relationship . Karandashev et al.  have recorded that in the initial phase of the relationship, Eros causes a decrease in avoidance, and anxiety diminishes, as part a dimension of the couple’s bonding process. As a further proof that the love style is positive, certain results highlight inverse proportionality between Eros and relational behaviour such as avoidance  or destructive communication behaviour―as identified by Gottman―including contempt, criticism, and defence , and with dysfunctional coping strategies such as interactional impulsiveness and dominance . Moreover, Couch et al.  have recorded that Eros does not seem to correlate with the dysfunctional emotional reactions that couples often expressed in critical situations, such as emotional infidelity of the partner.
In a study by Galinha et al. , Eros appears to also have a mediation function between attachment and subjective well-being, at least in Mozambican and Portuguese participants―though not in American participants. This result suggests that a combination of secure attachment and Eros contributes in greater measure to subjective well-being in collectivist cultures―such as Mozambican and Portuguese cultures―as opposed to individualist cultures such as the American culture.
Despite the positive value Eros style in relationships is broadly confirmed, we have recorded a series of discrepant opinions. While Kimberly and Werner-Wilson  have observed a moderate correlation between Eros and dyadic coping, degree of affinity, and relational satisfaction, Adil and Kamal  recorded zero correlation with secure attachment and, instead, an existing correlation with the attachment style defined by Bartholomew and Horowitz  as “preoccupied” (preoccupied attachment style, distinguished by a negative perception of one’s self and others), though only in males. Goodboy and Myers  observed, instead, that Eros may exist in partners adopting negative relational behaviour, such as spying on the partner; the scholars argue that such behaviour may be adopted as a possible confirmation that the love relationship is experienced intensely and passionately. Ortalda and Clapetto  reported that Eros may even be correlated to feelings of jealousy. Smith and Klases  have observed that the length of a relationship is a significant predictor of the Eros style, but in a negative sense: the longer the relationships last, the less individuals show the love style. In the only reviewed research in which the scholars analyzed marital couples with the actor?partner interdependence model, some differences between husband and wife were observed. In fact, while a passionate attitude toward love of a couple’s partners influenced their own marital satisfaction (albeit to a lesser extent in the husbands) (actor effect), only the wife’s Eros style had a significant effect on her partner’s marital satisfaction (partner effect).
Agape love style and its relational correlates
Distinguished by altruistic attitudes and behaviour expressed by people that are most interested in providing support, care, and respect to the partner, this love style is positively correlated to relationship quality , length of the relationship , and relational satisfaction   , regardless of the level of education, religiousness, or gender . Moreover, this type of partner: always tends towards a more secure attachment  ; considers commitment an important characteristic in choosing a partner  ; tends towards avoiding destructive communication behaviour―such as that identified by Gottman, including contempt, criticism, and defence  ―and negative strategies for conflict resolution, such as dominance, but―on the other hand―uses positive modes such as compromise . As recorded by Vedes et al. , a high level of Agape facilitates support to a stressed partner, and the joint effort to avoid stressors, although the latter coping type seems to be rarer in couples who have been together for longer. Furthermore, couples adopting such love type do not seem to show negative relational behaviour, such as jealousy or spying . Couch et al.  have recorded that Agape couples tend to not show dysfunctional reactions after having been cheated on by a partner. Nonetheless, when a relationship ends Agape males in particular report that they feel negative emotions .
As for Eros, results that are partially contradictory with the majority of research―which emphasizes its positivity―have been recorded. For example, Agape is recorded to not be correlated to attachment security , but rather to an anxious dimension of attachment  and pathological love .
Moreover, in terms of the connection between Agape style and relational satisfaction, Fehr et al.  observed it does not exist, Vedes et al.  found a greater presence in women, and Kimberly and Werner-Wilson  found a greater presence in men. This last result has been confirmed also in the research of Gana et al.  who used the actor-partner interdependence model. In fact, they observed only the effect of a husband’s Agape style on his own marital satisfaction (actor effect). Neither significant result regarding the effect of a wife’s agape style on her own conjugal satisfaction (actor effect) nor the effect of each partner’s Agape style on the relational satisfaction of the other one has been found.
Ludus love style and its relational correlates
With its playful and uncommitted attitude towards love, and its inverse proportionality with the intensity of the love sentiment , this style is generally regarded as a risk factor for the quality and stability of the romantic relationship. Coherently with its theoretical definition, and in a couple’s relationship pathway, the Ludus style appears to affect all development, maintenance, and dissolution phases, in terms of weak effort in the relationship, lack of care for one’s commitment or that of one’s partner, and positive feelings upon termination of the relationship  .
In the relationship building phase Ludic people tend to desire a lack of closeness  and to mistrust one another from the very beginning, although they nonetheless show signs of desiring closeness, and show fluctuations in avoidance . At the same time, though generally experiencing relational dissatisfaction   , ludic people make attempts to keep the relationship alive, though they do so through negative behaviour such as destructive conflict, infidelity, avoidance, a and stimulation of jealousy in the other, as well as spying .
Ludus is considered a good predictor of behaviour triggering jealousy in the partner   and destructive communicative behaviour such as that identified by Gottman as The Four Horsemen of the Apocalypse . In conflict situations, Ludus couples tend to adopt―rather than constructive strategies such as compromise―destructive strategies, such as dominance and a greater impulsiveness in interactions . Couch et al.  noted that when Ludus partners are cheated on, they do not manifest post-traumatic physical and psychological symptoms. Furthermore, Ludus is correlated to the avoidant form of attachment, as it is confirmed how partners with a playful attitude towards love tend to build adult insecure-avoidant attachment relationships .
Despite such clear and confirmed correlation between ludic behaviour and risk factors for the quality and duration of a relationship, certain research projects highlight gender differences and―as supported by Vedes et al.  ―hint how, still today, the love style is more socially accepted and considered more normal by and in men than in women. In fact, while in the view of Vedes et al.  relationship dissatisfaction is more frequent in ludic women rather than in men, Neto and Pinto  reported that adult men go as far as saying they are satisfied of their love life, whilst the love style appeared to be irrelevant in love satisfaction levels of young adults and older adults. Also in terms of a correlation with the preoccupied attachment form, Adil and Kamal  observed it is directly proportional in men and inversely proportional in women.
Storge love style and its relational correlates
There is a lack of research reporting significant data concerning this love style, based upon friendship and spending time with one another. It is considered a good predictor of married life quality  ; it is positively correlated with dyadic coping  and a progressive development of secure attachment  ; and in adults and older adults it is correlated with satisfaction in love life . Moreover, it is associated to functional strategies to solve conjugal conflict―such as compromise―and is inversely related to dysfunctional strategies such as impulsiveness in interaction . Couch et al.  reveal how there is no evidence that persons adopting this style, along with Eros, Pragma, and Agape, suffer negative consequences on the physical-psychological health following emotional infidelity by a partner.
While Galinha et al.  noted an absence of association between relational satisfaction and secure attachment, in the meta-analysis performed by Acevedo and Aron  it was recorded that the style is moderately correlated with relational satisfaction, mostly in long-term relationships rather than short-term relationships. It also appears to be a common style in long-term relationships, and when the relationships end, jealousy seems to be the main motivation . On the other hand, Smith and Klases  observed how the longer the relationship, the more unlikely it is that partners show such friendly attitude in love.
Pragma love style and its relational correlates
Typical of people who express a pragmatic and rational attitude towards love, and for this reason tend to choose the partner based upon the characteristics they believe are important to them , Pragma appears to be linked to stable relationships , partially to the quality of married life , and to satisfaction in the relationship by adults and older adults . It also contributes to the subjective well-being of people . In conflict situations, pragmatic people generally utilize strategies such as compromise and avoidance , and when they suffer emotional infidelity by their partner, they do not have strong reactions . Partners with this style do not appear to build an “anxious”, fearful attachment style―distinguished by a negative perception of one’s self and others, according to the typology identified by Bartholomew and Horowitz  ―but instead show uncertainty and fluctuations in the formation of an emotional attachment . Galinha et al.  have not recorded any influence of this love style on secure attachment and on perception of the relational satisfaction of the partner.
Mania love style and its relational correlates
Mania is the expression of a manic attitude towards love, implying possessive and obsessive behaviours: it is considered the purest form of romantic obsession  . It is perhaps due to such characteristic that it is considered and consolidated as an important risk factor in quality of married life. Despite it involves people that tend to commit to the relationship , such people do not appear to be able to build long-term relationships  or satisfying relationships , with a few exceptions. In fact, Neto & Pinto  recorded a correlation between love life satisfaction in manic male adults, but not females. Mania is a strong predictor of negative relational behaviour. It is correlated to jealousy  and exists in people expressing pathological jealousy  and pathological love  , and that tend to manifest jealousy-evoking behaviour in the partner, even when they are shown affection by the latter . Partners adopting a manic love style tend to express an excessive need to be reassured by the partner , emotional highs and lows in the ability to be close to him/her , an anxious-ambivalent attachment style , and preoccupation for the relation and its termination . On the other hand, Smith and Klases  recorded an inverse proportionality with the anxious component of attachment. Manic people tend to exercise negative relational behaviour to keep the relationship alive, such as destructive conflict, infidelity, allowing control and spying . In their cultural analysis, Galinha et al.  revealed how Mania is inversely proportional to secure attachment in their Mozambican sample, but not in the American or Portuguese participants.
It is directly proportional to destructive communication behaviour such as that identified by Gottman , and is the main predictor of negative reactions following infidelity by a partner, in that people adopting this style tend to: live infidelity in a traumatic manner, express unresolved feelings related to the event experienced, and suffer physical symptoms, acute stress, unease, anxiety, depression, and struggle to forgive .
The results of the researches and studies considered in this review allow us to formulate an initial, though general, argument related to the importance of love and the various behaviours it is expressed with that affect quality and duration of a relationship. It is thus also a topic relevant to the field of psychology, and not only a matter for writers, artists, and poets. In the very conceptualization of love, aspects such as happiness, satisfaction, intimacy, passion, and commitment are central dimensions. It is sufficient to remember the Triangular Theory of Love by Sternberg and the numerous research projects referencing it and highlighting how the components identified by the scholar have a considerable importance for the relational satisfaction of partners  . Furthermore, Fricker & Moore  claimed that love styles themselves branch from the adult attachment theory, and thus a clearer comprehension of relational satisfaction may be obtained by combining the two perspectives.
This review also appears to confirm the variability of ways to live love and, in particular, that love styles seem to be separate from one another, and each provides different information on the quality and duration of a relationship, though a clear and linear model of correlation has not emerged to this day. This leads us to believe that there exists a complex articulation of love and relational variables. A significant example is provided in the research by Hammock & Richardson , which revealed different correlations between different love styles and variables in the relational phases: choosing a partner, maintenance, and termination of the relationship. At the same time, various researches underline how there continues to often exist gender inequality in the ways and directions in which the correlations between love styles and relational dimensions manifest themselves. This makes the widespread interpretation that men and women tend to express different attitudes towards love and love relationships more problematic  . In this perspective, it is believed that women are more oriented towards relationships and love, thus more influenced by love styles compared to men  . A further source of complication is the life cycle of a love relationship. In terms of love styles, the relational satisfaction curve seems to overcome the U-shape―as Vaillant and Vaillant  observed―and follows a varying proportionality to the life phases of a couple  .
Moreover, the research papers reviewed emphasize not only the distinction between love styles, but also the variability within each style as opposed to the different factors of relationship quality. In fact, although the results of research and studies mostly agree in stating the importance of Eros, Agape, and Ludus in the quality of a love relationship―a positive effect in the first two cases (as factors of protection and resources) and a negative effect in the third case (as a factor of risk and vulnerability)―there is in any case a certain degree of variation and contradiction in the results recorded for the different styles. For instance, while almost the entire pool of research projects records a correlation between Eros and positive characteristics of a relationship, certain other cases highlighted a correlation with negative behaviour in the relationship maintenance phase, such as spying on the partner , and―in males―with preoccupied attachment style .
Despite the development we may record in terms of interest for research on love styles and types, as well as their effects on well-being, personal and relationship health, there still remain a number of matters to deal with, which the articles reviewed agree to mainly be the method-related aspects. We have indeed recorded how the majority of projects use convenience sampling but―although this method is appropriate in certain circumstances, especially in exploratory research performed to generate new ideas―as stated by Lin and Huddleston-Casas , it is necessary to also implement random sampling in order to know and generalize the results. Moreover, the samples were generally composed of students, and thus―as stated by Neto and Pinto  ―were not representative of the wider population of people involved in love relationships. In addition to this, the samples mostly comprised individuals and not couples. This prevented from recording what actually occurs in a relationship, and thus the possibility of performing a dyadic assessment, which is a method gathering wide attention in the field of research on relationship quality    . In fact, a number of studies highlights the possibility of a reciprocal influence between partners, also in terms of the attitude towards love . Using a dyadic approach, for some of love styles (as Eros and Agape) the reviewed research of Gana et al.  showed husband-wife non-independence in marital satisfaction. Therefore, acknowledging how the love approach of a partner influences not only his/her perception, behaviour, attitude, and feelings towards the relationship, but even those of the partner, is a particularly interesting goal in the study of love. Indeed, upon a systemic approach, it may be stated that the influence one may have on his/her personal and relational health and well-being does not only depend on one’s own way of being, but also that of the partner.
Another element of vulnerability is the use of cross-sectional research design, which is widely used but nonetheless limits the possibility of generalizing results and to make inferential conclusions. Therefore, while it is easily presumed that love styles belong to a person before he/she gets involved in a love relationship, at the moment bidirectional or even opposite effects may not be ruled out. Thus, future research shall focus more on a longitudinal design in order to observe the path of love styles . Besides, longitudinal studies may also represent a useful analysis of the transformations of love and the related attitudes and behaviour throughout the couple’s relationship life. In the review, it emerges that there are authors who report the need to distinguish short-term and long-term relationships in an assessment of the effects of love (see, for example, the meta-analysis by Acevedo & Aron, . Clearly, to consider the development of a relationship also implies an assessment of the different dimensions and aspects that may exist in a couple’s relational life, such as the existence of parenthood or not. There is a true lack of research on love styles in the latter scope; this is further attested by the fact that, on the other hand, in research concerning relationship quality it is widely documented how the presence of sons may become a risk factor   .
Moreover, the papers taken into account in this review use self-report tools, which it would be necessary to pair with other techniques such as observation, qualitative interviews, and neuroimaging. This would allow to obtain a more detailed picture of phenomena, such as love, which have complex and multidimensional characteristics, as indeed underlined by Graham  upon conclusion of his meta-analysis. This broad and integrated assessment of different techniques may even be especially useful in the evaluation of sentimental relationships and―as observed in the past by Weiss  ―may imply a bias related to the tendency to observe relational aspects positively when people are happy and satisfied of their marital life.
Although our review allows to have an idea of the state-of-the-art of knowledge and criticalities concerning this topic, and to offer indications for further research and its practical implications, it is nevertheless wise to keep into account certain limits of this study. First of all, it must be considered that the review was conducted by limiting the selection to contributions published on peer-review journals in Italian and English. Moreover, there was a focus on relational aspects and dimensions that shall be in any case not dissociated with personal, social, and cultural variables, which are also widely analysed in literature on love styles. Furthermore, we carried out a systems research rather a meta-analysis―which is generally considered more accurate in gaining knowledge on given phenomena. This choice was due to the fact that the empirical research on love styles―though expressing interest in a deeper analysis of the topic―are nonetheless not sufficiently abundant so as to allow a reliable inference on their importance and effects, in order to comprehend the relationship dynamics and thus intervene on relational health and well-being in the different contexts. A further limit is the fact that what we present is a narrative synthesis, subject as such to the arbitrary interpretation of the authors.
Nonetheless, the review widely highlights the relevance of the topic in the assessment of relationship health. Further developments on the knowledge of this field, with broad-spectrum studies and researches that may take into account the complexity of the phenomenon and its peculiarities are therefore desirable. Among these, the most relevant seem to be the mechanisms in couple matching, in that love and its approaches primarily find expression in a sentimental relationship. Besides, it is in fact the complexity of the aspects and mechanisms highlighted that suggests the opportunity to reflect upon the suitability and exhaustiveness of a categorization of love in mutually nullifying love styles and types, in order to investigate a possible natural dimension of the structure.
Further in-depth analyses may even have interesting implications on the praxis, both in terms of assessment and in terms of preventive action. Hendrick  affirms the importance of an assessment of love styles in patients dealing with relationship issues. Knowledge of love styles, as asserted by Ortalda and Clapetto , may allow an identification of the specific love style related to well-being or to unease or struggle, thus aiding the diagnostic phase in a clinical intervention. It is especially the identification of the polysemy of love and the different effects that living such sentiment may have on a relationship that―as claimed by Neff and Karney  ―may direct the focus not so much on the question of if and how much partners love each other, but how they love each other. Moreover, considering the importance of a dyadic assessment of issues in a couple, knowledge of the combination of love styles in partners may help understand such criticalities. Think of a couple in which the husband is pragmatic (Pragma) and the wife is romantic and passionate (Eros): the male analyses the relationship status and that which the wife can offer, while the female loves to let herself go without any calculation; such couple may be at risk. Even the clinical intervention should be addressed towards the distinguishing traits of the love styles existing in couples that are dysfunctional, conflicting, or in a crisis. Literature includes a number of experiences that may help understand how to address a clinical intervention focused on love. Even Yatim, Jusoh, Saper and Mukti  observed how the Agape love style is central to counselling, and discussed its implementation in a type of professional intervention that it is named after (Agape Love Counselling).
In conclusion, the research significance on love, and in particular on love styles, is associated especially with the knowledge about the couple relationships and their functionality. In fact, the information that we can obtain from the analysis of this topic permits to enrich the range of risk and protective factors of marital quality and stability. Besides, the practical significance of these studies concerns mainly the attainment of the awareness about the relevance of love in the prevention and therapy of relation dysfunctionality.
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