A sexual selector is someone who actually selects who they want to date instead of proposing. Large populations of people who sexually initiate less than those who desire them generally become sexual selectors. Throughout most, if not all, human history, women have been sexual selectors.
15% of responders on ForeverAlone thought that women could only be involuntary celibate "in extenuating circumstances such as deformity, disability, and severe mental health issues." In the western world, increasingly, men are opting out of freemixing with women.