The science of matching: What makes couples truly compatible?
Anna and Thomas have been in a happy relationship for seven years—even though at first glance they couldn't be more different. She is extroverted and spontaneous, he is analytical and methodical. In contrast, Julia and Markus's relationship failed after only a year, despite their impressive similarities in interests and lifestyle. Such examples raise a fundamental question: What really makes people compatible?
Pop culture offers us contradictory answers: “Opposites attract” versus “birds of a feather flock together.” Dating apps promise perfect matches based on everything from zodiac signs to music tastes. But what does science actually say about this? Which factors actually predict long-term relationship success?
In this article, we go beyond intuition and popular wisdom and delve into evidence-based research on romantic relationships. We highlight which compatibility factors science has identified as crucial, whether similarity or difference works better, and how these findings can contribute to a better understanding of successful partnerships.
The evolution of matching science
The attempt to determine optimal partner constellations is as old as humanity itself. From ancient oracles and horoscopes to arranged marriages based on family and socioeconomic factors, the quest for the “right” match is deeply rooted in our cultural history.
Scientific research into mate selection only really took off in the 20th century. In the 1950s, sociologist Robert Winch developed the “complementarity theory,” which postulated that people seek partners whose needs and personalities complement their own. Donn Byrne formulated the opposite position with the “similarity theory,” which argued that we are attracted to people who share our attitudes and values.
Modern matching research combines findings from evolutionary and social psychology, neuroscience, and behavioral research. According to current research, romantic love is no longer considered merely a feeling, but rather a “functional biological system”—a motivational state typically associated with the desire for long-term commitment.
Methodologically, science faces particular challenges: partner choice and relationship success are multidimensional constructs. The most valid studies use longitudinal designs that track couples over years or even decades and combine self-reports with behavioral observations. Only such rigorous research approaches make it possible to distinguish between factors that are actually significant and those that are only superficial or short-term.
The key predictors of relationship success
Gottman's “Four Horsemen of the Apocalypse”
John Gottman's groundbreaking research has shown that certain patterns of interaction can predict relationship success or failure with astonishing accuracy. Gottman can predict with 94% accuracy which couples will separate—not based on how often they argue, but how they argue. The “four horsemen of the apocalypse” he identified—criticism, contempt, defensiveness, and stonewalling—are the most reliable predictors of relationship failure.
Contempt, which manifests itself in sarcastic remarks, eye rolling, or open mockery, is particularly toxic. It signals a fundamental disregard for one's partner and is the strongest single predictor of divorce. Conversely, positive communication patterns—active listening, empathy, and constructive problem-solving—are associated with relationship stability.
Personality and compatibility
Personality research, especially the Five Factor Model (Big Five), is often used in dating contexts, but modern research shows that personality is far more dynamic than is often assumed. People exhibit different expressions of the same personality dimensions depending on the context, stage of life, and social situation.
This insight has important implications for partner selection: instead of looking for static “personality types,” it makes more sense to understand your own context-dependent patterns. When do you show your most cooperative side? In which situations do you react particularly sensitively to stress? How does your need for social stimulation change depending on your life circumstances?
This self-reflection makes it possible not only to recognize compatible partners, but also to understand under what circumstances one's own personality thrives best in a relationship. Serious matching approaches therefore use personality dimensions less for direct matching and more as a tool for self-awareness and conscious partner selection.
Attachment styles and their interactions
Attachment styles, which are based on early relationship experiences, significantly influence our romantic relationships in adulthood. Research distinguishes between secure, anxious-ambivalent, and avoidant attachment.
Secure attachment is characterized by trust, open communication, and emotional support, and correlates strongly with relationship satisfaction. Anxiously attached people tend to fear loss and cling, while avoidantly attached people have difficulty with closeness and intimacy.
The compatibility of attachment styles follows complex patterns: two securely attached partners form the most stable constellation. A securely attached partner can “balance” an anxiously or avoidantly attached partner and improve the quality of the relationship. The most challenging combination is between anxiously and avoidantly attached partners, who often fall into destructive pursuer-distancing dynamics.
Values, goals, and life plans
Contrary to popular belief, shared hobbies and interests are only weak predictors of long-term relationship success. Much more important is agreement on fundamental values and life goals.
Studies show that similarities in areas such as religiosity, political views, attitudes toward children, finances, and place of residence are stronger predictors of relationship satisfaction than shared leisure activities. These “deal-breaker” issues concern central aspects of life planning and often lead to irresolvable conflicts when there is disagreement.
Emotion regulation as a key factor
An often overlooked but scientifically well-documented predictor of relationship success is the ability to regulate emotions. Couples who use constructive strategies to cope with negative emotions and conflicts show significantly higher relationship satisfaction and stability.
Constructive strategies include dialogue (active, constructive discussion) and loyalty (passive, constructive expectation of improvement). Destructive strategies such as escalation (accusations, aggression) and withdrawal (ignoring, reducing contact) correlate negatively with relationship quality.
The ability to regulate one's own emotions and respond empathetically to one's partner's feelings creates an emotional foundation that helps couples weather difficult phases of life and inevitable conflicts.
Similarity versus complementarity
One of the most fundamental questions in compatibility research concerns the tension between similarity and complementarity. Do opposites really attract, or do similar partners work better together?
The research findings are mixed: attraction between people results from assessments of a potential partner's ability and willingness to promote one's own goals and needs. Various factors are of varying importance here:
Areas in which similarity is particularly important:
Core values and beliefs: religion, politics, family orientation, ethics
Life goals: career ambitions, desire to have children, lifestyle preferences
Intellectual level: educational background, cognitive style, communication patterns
Areas in which complementarity can be advantageous:
Personality traits: introversion/extraversion, planning orientation/spontaneity
Role distribution and skills: complementary strengths and weaknesses
Interaction styles: active/passive, leading/following (as long as these are not extremely pronounced)
The “sweet spot” theory states that successful couples find an optimal balance between similarity and difference. Too much similarity can lead to boredom, while too many differences can create conflict. However, this balance is not the same for all couples—some thrive with more differences, while others need more similarities.
Long-term studies spanning several decades show that similarity in core values and communication styles is more important for long-term relationship satisfaction than initial passion or superficial similarities. Interestingly, couples in collectivist cultures, where marriages are often based on compatibility in values and family harmony, report similar or even higher satisfaction scores than couples in individualistic cultures, who marry primarily on the basis of romantic love.
From theory to practice: Scientifically based matching
Translating scientific findings into practical matching approaches is a complex task. Modern matchmaking platforms use various strategies:
Quantitative approaches measure numerous variables using standardized questionnaires and algorithms that combine similarity and complementarity in weighted formulas. The advantage lies in objectivity and scalability, while the weakness is that they can hardly capture subtle personality facets or the “chemistry” between people.
Qualitative approaches emphasize deeper psychological profiles and contextual factors. They can be more nuanced, but are more difficult to standardize and more prone to subjective bias.
Research on dating decisions shows that people consider both “deal makers” (desirable qualities) and “deal breakers” (exclusionary criteria) when choosing a partner. Interestingly, deal breakers often have a stronger influence on decision-making—we filter out potential partners more quickly based on unacceptable qualities than we select them based on positive attributes.
Reputable dating platforms integrate scientific findings by:
Focusing on proven compatibility predictors rather than superficial characteristics
Differentiated assessment of personality, values, and communication styles
Transparency about the basis of their matching approach
Realistic expectation management regarding predictive power
The LemonSwan approach is based on a combination of these evidence-based factors, with a particular focus on values, communication styles, and long-term relationship goals—factors that have been scientifically proven to be particularly relevant for lasting relationships.
However, it is important to note that no algorithm can make perfect predictions. Romantic love retains an element of unpredictability, and even the most scientifically sound methods can only increase the probability of a successful relationship, not guarantee it.
The science of long-term intense romantic love shows that it is a rare but real phenomenon in which some people experience intense attraction and sexual chemistry even after many years in a relationship—unlike the early obsessive phase of passionate love, as insecurity and fear are absent. This lasting passion can be fostered through conscious relationship maintenance.
Conclusion: Summary of key findings
Scientific research into partner compatibility has made considerable progress in recent decades. The key findings can be summarized as follows:
Communication patterns are the strongest predictors of relationship success—how couples talk to each other and resolve conflicts is more important than what they talk about.
Values and life goals are more fundamental to long-term compatibility than shared hobbies or physical attractiveness.
Emotional stability and constructive emotion regulation form the foundation of successful relationships.
Attachment styles significantly influence relationship dynamics, with secure attachment being associated with higher relationship quality.
When it comes to personality traits, a balanced mix of similarity and complementarity may be optimal.
These scientific findings offer valuable guidance, but romantic love remains a complex phenomenon that can never be fully reduced to formulas. The “chemistry” between two people—that subtle interplay of attraction, timing, and shared experience—remains an essential component of successful bonds.
For your own choice of partner, this means reflecting on your core values and life goals and looking for compatibility in these fundamental areas. Pay particular attention to communication patterns and emotional reactions in challenging situations. And don't forget: the most scientifically sound choice of partner is only the beginning—long-term relationship success requires continuous investment, communication, and a willingness to grow together.
The future of science-based matchmaking lies in the increasing integration of neurobiological, psychological, and sociocultural insights. As research progresses, we will gain a better understanding of the complexity of romantic compatibility—not to demystify the magic of love, but to help more people find fulfilling and lasting relationships.
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