Abstract
Cross-sex friendships are often characterized by psychological and behavioral patterns consistent with underlying mating motivations, and many romantic relationships begin as friendships. Despite the prevalence of mating outcomes in cross-sex friendships, little is known about the courtship behaviors in cross-sex friendships that translate into these outcomes. Guided by parental investment theory, sexual economics theory, and the principle that courtship behaviors are calibrated to the mate preferences of the courted sex, we elaborated and tested multiple novel predictions about a candidate courtship behavior in cross-sex friendships: financial provisioning. Findings provided robust support for half a dozen sex-differentiated predictions. First, men (N = 147) reported that they pay for more of bills shared with cross-sex friends, a perspective corroborated by reports from women (N = 441). Second, men's, but not women's, interest in mating with their cross-sex friends predicted their financial provisioning behavior. Third, women, but not men, perceived cross-sex friends who financial provision them to be more interested in mating with them. Notably, all these findings were explained as between-person differences rather than within-person effects. That is, men did not provision some female friends more than others depending on their attraction to those specific friends. Rather, some men consistently provisioned across their cross-sex friendships, whereas others did not. This pattern suggests that some men are inclined to view cross-sex friendships as mating opportunities whereas others do not, which may help explain some of the variation in platonic versus mating outcomes of cross-sex friendships. Collectively, these findings offer multiple new insights into the psychology underpinning cross-sex friendships.