Global Study Uncovers Complex Rules of Romantic Compatibility

The study, appearing in the *Journal of Research in Personality*, surveyed 41,606 adults in romantic relationships across 74 countries. Respondents rated themselves and their partners on nine traits—health, kindness, physical attractiveness, religiousness, resources, social class, education, political orientation and age—using eleven-point scales, and completed the Triangular Love Scale and a satisfaction measure. Analyses showed that kindness and physical attractiveness were the strongest predictors of relationship quality; self- and partner-ratings of kindness together explained about 21 % of the variance in satisfaction. Participants reported the highest love and satisfaction when they perceived their partners as kinder and more attractive than themselves. By contrast, similarity in political orientation predicted higher quality, with larger ideological gaps linked to lower satisfaction regardless of direction.

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Cross-cultural analysis revealed that societies with high human development, individualism, gender equality and relational mobility amplified the impact of kindness and attractiveness on happiness, whereas less modernized contexts showed stronger effects for matching on social class and education. Gender differences were minimal; both men and women displayed similar patterns, with only minor exceptions such as men reporting slightly higher passion with younger partners.

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Lead author Marta Kowal of the University of Wroclaw’s Institute of Psychology said the results challenge the popular “opposites attract” belief, showing that similarity matters for value-based traits while partner idealization drives satisfaction for universally valued traits. She also noted that the large, culturally diverse sample addresses the WEIRD bias of earlier research.

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The authors acknowledge that the study relies on self-reported, single-partner data, capturing perceived rather than objective similarity. This design cannot determine whether high satisfaction leads to favorable partner ratings or vice versa, limiting causal inference.

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Because only one partner’s perspective was collected, it remains unknown whether the observed patterns hold when both partners are surveyed. The cross-sectional nature of the data also prevents assessment of changes over time.

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• “The saying goes that opposites attract. However, scientific evidence largely suggests otherwise, people who are more similar tend to have more satisfying relationships,” — Marta Kowal, Researcher

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• “Kindness was the strongest predictor: participants’ self-ratings and their ratings of their partners’ kindness together accounted for approximately 21% of the variance in relationship satisfaction, which is quite substantial for a single trait assessed with a single item.” — Marta Kowal, Researcher

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• “I was actually quite surprised by small gender differences,” — Marta Kowal, Researcher

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• “This means that what we are capturing is perceived similarity and perceived partner traits, not actual similarity or objectively assessed traits.” — Marta Kowal, Researcher

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The researchers recommend longitudinal dyadic studies that survey both partners over time to separate perceived from actual similarity and to observe how trait importance evolves as relationships progress.

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