Benevolent sexism (BS) contains prescriptive partner expectations that should foster an intolerance of discrepancies between partners and warmth/trustworthiness ideal standards. This longitudinal study tested whether endorsing BS magnifies the degree to which warmth/trustworthiness partner‐ideal discrepancies are associated with willingness to dissolve relationships. Heterosexual couples (N = 88) reported their partner‐ideal discrepancies, willingness to dissolve the relationship, and their partner's willingness to dissolve the relationship every 3 months for 1 year. Greater partner‐ideal discrepancies were associated with subsequent increases in willingness to dissolve the relationship, but this was stronger for people who endorsed BS. Partners of women who endorsed BS also perceived this greater willingness to dissolve the relationship. These results demonstrate that the prescriptions within BS undermine the stability of ongoing relationships.