Negative postcoital emotions (NPEs) are understood as a disorder by some authors, but little is known about their evolutionary significance, etiology, and prevalence. We surveyed samples from the United States, Canada, Brazil, and Norway to test predictions regarding the following evolutionary hypotheses: Three groups of NPEs exist, related to (a) having a lesser or (b) a greater perceived desire for bonding and commitment than one’s partner, or to (c) the maintenance of sexual reputation. Additionally, (d) we hypothesized a Sex by NPE dimension interaction, whereby men have higher levels of NPEs related to a lesser perceived desire for bonding relative to women, and women have higher levels of NPEs related to greater perceived desire for bonding relative to men. Results corroborated the existence of the 3 dimensions of NPEs, and the associations found between them and indicators of mating effort, attachment anxiety, relationship satisfaction, and mate quality supported most predicted design features across samples. The hypothesized sex differences were supported in all samples. We argue that NPE factors have an important functional basis in sexual strategies, and the factor comprising guilt, shame, and related emotions facilitates the maintenance of sexual reputation. The capacity to experience NPEs appears to have evolutionary functions, and we question its classification as pathological, considering the harmful dysfunction theory of pathology. Finally, we report prevalence data indicating that NPEs are much more common than previously speculated, with frequencies that were highly comparable across samples.