Partner aggression negatively affects well-being in ways that the people experiencing aggression may not expect. Individuals (n = 171) who reported aggression by their current partner completed a longitudinal study. At the start of the study, participants rated their current happiness and how happy they expected to feel if their relationship were to end. The data revealed a partner aggression–unhappiness link and evidence of misforecasting future happiness: Committed individuals overestimated their unhappiness after a breakup because they expected worse things from a breakup than actually materialized, and people who experienced high partner aggression overestimated their unhappiness because they became more happy without the partner than they had expected. Forecasting unhappiness after a breakup predicted staying in an aggressive relationship. In aggressive relationships, bias occurs not only in forecasting future happiness but also in misreading how badly one feels now.