<p>Contexts of low income create considerable stress, which can influence romantic relationship functioning. In the United States, safety net programs provide cash assistance to families with low incomes. The amount of funds provided varies by state, affording opportunities to test whether larger cash assistance policies protect relational wellbeing. This study examines whether variations in state-level social safety net benefits (i.e., Temporary Assistance for Needy Families and Earned Income Tax Credit) and cost of living protect mothers with low income from the effects of economic hardship on romantic relationship conflict frequency and dissolution. Data were drawn from romantically partnered mothers from Years 1 (ca. 2001) and 3 (ca. 2003) of the Future of Families and Child Wellbeing Study (<i>N</i>s = 1440–2070). Regression models with robust standard errors evaluated main and interactive effects of economic hardship, cash assistance, and cost of living on relational outcomes. Cost of living and cash assistance did not interact to buffer the influences of economic hardship on conflict frequency or relationship dissolution. In post-hoc analyses, for mothers below the poverty line, greater cash assistance was negatively associated with conflict frequency in areas with higher cost of living (0.46 SD above the sample mean). Cash assistance programs in the United States may provide inadequate funds to benefit the relational wellbeing of families with low incomes.</p>