We use interdependence theory and the inertia model to examine how gender and daily relational sacrifices predict daily variability in relationship commitment across a week in 43 U.S. couples who are unmarried cohabitors expecting their first child together (total of 455 days of data). We examined three variants of daily relational sacrifices: frequency, ease, and awareness for both individuals and partners, and we tested for gender differences. Using an Actor Partner Interdependence Model (APIM), we found that both women and men reported lower variability in commitment when men were perceived as highly aware of the sacrifices made for them. Additionally, women experienced lower variability in commitment when their male partners reported engaging in easier sacrifices. In contrast, women reported higher variability in commitment when they reported greater frequency of sacrifices for their partner. The results can be of practical use for practitioners working with expectant cohabitors and their partners given the unique role gender plays relative to how sacrifices shape variability in daily commitment.