Despite cohabitation becoming increasingly equivalent to marriage in some of the most ‘advanced’ Western European societies, the vast majority of people still marry. Why so? Existing theories, mostly based on various approaches tied to cognitive decision-making, do not provide a sufficient explanation of the persistence of marriage. In this article, we argue that feelings attached to marriage, i.e. the affective evaluation of those involved in a partner relationship concerning marriage as opposed to cohabitation, explain the persistent importance of marriage as an institution. We argue that socialization, biological and social-structural factors affect these affective evaluations. We provide a test of our hypotheses using a longitudinal study of young adults in the Netherlands. The results of our analyses are consistent with a central role of feelings in the decision to marry, as well as with a role for key moderating factors such as gender.