This chapter asks what light the well-known but little understood story of Augustine’s relationship to the mother of his first child can shed on our understanding of marriage as an asymmetrical institution in the Roman period. Reviewing the evidence that both pagans and Christians in late antiquity expected a ‘double standard’ for men and women where marital fidelity was concerned, we suggest that Augustine’s On the Good of Marriage argued for a new marriage ethics based on sexual symmetry, capturing a new spirit of criticism for the double standard in fourth-century preaching, and that Augustine invoked his own experiences (as recounted in the Confessions) in order to drive home his argument.