Abstract
Mate guarding occurs in both males and females, however there may be sex differences in the reasons why they mate guard each other. Men are controlling to restrain their partner from being unfaithful. Males respond this way to ensure paternity certainty so they do not waste resources in an unrelated child. We hypothesized that women who are controlling would report less investment in their relationship and having better potential mating alternatives than those who are less controlling. 1,069 women were recruited from a small university and online to participate in the study. Results support this hypothesis. Mating alternatives, having cheated on a partner, and sexualizing others predicted women's control of their partner.