Abstract

Although monogamy, the exclusive bonding with a specific partner, is one characteristic of modern human mating, long-term romantic relationships inherently possess the commitment problem, which is the conflict between maintaining a relationship with a certain partner and seeking attractive alternatives. Frank has argued that love and passion help solve this problem because they make individuals commit voluntarily to the relationship, leading the other party to also be committed with less concern over being cheated on or rejected. Combining this idea with the comparative socio‐ecological approach, we hypothesize that passion will be more pronounced in social environments in which people have greater freedom to choose and replace their partners (i.e., high relational mobility) than in societies in which relationships tend to be more stable and hard to change (i.e., low relational mobility). To test this hypothesis, we compared Americans (living in a society with high relational mobility) and Japanese (living in a society with low relational mobility). As predicted, Americans were more passionate toward their romantic partners than Japanese, and this cultural difference was partially explained by the levels of perceived relational mobility in participants’ local ecology. Moreover, more intense passion was found to lead to greater commitment behaviors in both societies. The importance of taking socioecological factors into consideration for the theory of the adaptive function of interpersonal emotions is also discussed.