The game of affinities, which, depending on the context, favors more or less the establishment of relationships with people sharing similar characteristics, is discussed here. We begin with the formation of couples and the well-studied phenomenon of "homogamy," and then broaden the focus to its equivalent for general social relationships, "homophily." Social inequalities leave their mark on the characteristics of networks, on their arrangements with social circles, and on the evolutions of the interpersonal relationships that compose them. Even the elective affinities that we would like to believe as "free" of these burdensome social categories are in part subject to them. This chapter describes what can be called "soft segregation," that is, the fact that freely chosen relationships can paradoxically contribute to the fragmentation of the social world.