People do not always look for mates, and frequently choose to stay single, at least for some time. This study puts forward an evolutionary framework in which people prefer to stay single because doing so either increases their future mating success or because they have traits which prevent them from being able to attract a mate. The study aims further to identify the specific reasons that drive people to stay single, to classify them in broader reason categories and to investigate their contingencies. Accordingly, by using a combination of qualitative research methods, Study 1 finds 76 different reasons. By using a sample of 1096 participants, Study 2 applied first order principal components analysis and classified these reasons to 16 reason factors. By using second order principal components analysis, it classified these 16 reason factors to three reason domains. Finally, it was found that sex, age and personality significantly predict the reasons that drive individuals to stay single.