“…Moreover, motivations for sex may be interchangeable within a given dyad over the course of days, weeks, months, and years, with changes supported by trust and distrust experiences developing through repeated encounters, both sexual and nonsexual (Mullinax et al, 2016a). Specific sexual behaviors-first coitus or first receptive anal sex, for example-are used to signal trust and serve as "gifts" to the partner, in part to maintain the dyad relationship (Carpenter, 2002;Norona, Welsh, Olmstead, & Bliton, 2017).…”