From the evolutionary perspective, maintaining a committed relationship is beneficial for reproductive success but involves risks such as losing a partner or infidelity. People typically prefer partners with similar mate value (MV) to avoid rejection. However, when a mate value discrepancy (MVD) arises, the partner with lower MV might employ mate retention strategies to maintain the relationship. This study investigated whether men with lower MV compared to their female partners used cunnilingus more often and whether this effect was mediated by their motivation to satisfy the partner. Additionally, it tested the moderating role of men's perceived vulnerability to disease (PVD), predicting that men less concerned about disease would show a stronger link between MVD and cunnilingus frequency, given the health risks associated with oral sex. Data from 540 men in committed heterosexual relationships confirmed that a higher MVD-where the man's MV was lower than his partner's-led to more frequent cunnilingus, and this relationship was mediated by a greater motivation to sexually satisfy the partner. However, the moderating role of PVD was not confirmed. We explore the evolutionary perspective that men may perform oral sex on their partners as a mate retention strategy. This behavior potentially serves as a benefit-provisioning mechanism, compensating for discrepancies in mate value.