Life history theory predicts that individuals allocate finite energetic and motivational resources across competing fitness-relevant domains including mating effort, parenting, and alliance formation. Ovarian steroid hormones offer a proximate mechanism for this allocation: estradiol and progesterone fluctuate across the ovulatory cycle and have been implicated in shifts not only in mating-relevant psychology but also in social motivation and the prioritization of close relationships more broadly. Luteal-phase increases in progesterone have been linked to heightened social motivation, potentially reflecting preparation for the greater reliance on allies for resources and protection that accompanies pregnancy. Using daily urinary measures of estradiol (E1G) and progesterone (PdG) collected across a full ovulatory cycle from 68 naturally cycling women, this study examines within-person hormonal associations with empathy and prosocial helping directed toward two theoretically distinct targets: a male romantic partner or romantic interest, and a female same-sex acquaintance. This dyad-specific design allows direct comparison of the hormonal regulation of romantic versus same-sex affiliative sociality within the same individuals, offering a more precise test of the mating–alliance resource trade-off than prior designs that examined these domains separately. Results indicate that hormone associations interacted with target sex, target attractiveness, and analytic time scale, suggesting that the social affiliative system is context-specific and supports the mating–alliance trade-off account.