LAUSR

Abstract Compared to motivations for cross-sex friendship, little research has examined motivations for friendship between ex-partners after romantic relationship dissolution (i.e., post-relationship friendship; PRF). In Study 1, participants ( N  = 348) act nominated reasons for why someone might remain friends with an ex-partner. In Study 2, participants ( N  = 513) rated the importance of staying friends with an ex-partner for each reason given in Study 1 and completed the PID-5-BF and HEXACO to measure domains of clinically relevant and non-pathological personality. Principle component analysis identified seven categories of reasons for staying friends. Reasons that indicated that an ex-partner is reliable, trustworthy, and of sentimental value (i.e., reliability / sentimentality ) were given the highest importance ratings whereas reasons that indicated that continued friendship was practical (i.e., pragmatism ) were given the lowest ratings. Men rated pragmatism and sexual access reasons as more important than women did. Furthermore, antagonism scores on the PID-5-BF, and the Honesty–Humility and extraversion scores on the HEXACO predicted importance ratings for pragmatism and sexual access . Our findings are consistent with previous research and suggest that PRF may provide opportunity for ex-partners to exchange desirable resources (e.g., love, status, information, money, sex) after romantic relationship dissolution.