This article traces a genealogy of serial monogamy in Swedish policy documents (SOU) during the twentieth century. Analyses of renegotiations of marital morality, introduction of more liberal divorce laws, and the introduction of regulations of unmarried cohabitation show that societal norms as well as legal reforms have normalized serial monogamy as state regulation and social practice. The role of marriage as a societal stabilizer has increasingly been taken over by the idea of family, but interestingly durability and stability are concepts invoked during the process of decline of the ideal of lifelong marriage.