Drug use and condomless sex among sexual minority men in relationships: Whether relationship quality is a risk or protective factor depends upon what they believe their partners do.

Sexual minority male (SMM) couples tend toward behavioral similarity around cannabis use, illicit drug use, and sex with casual partners. Similarity in these behaviors may contextualize associations with relationship quality. This study tested the hypotheses that perceptions of partner (cannabis and illicit) drug use and sexual behavior would predict personal drug use and sexual behavior as well as moderate the association between relationship quality and these health outcomes. Recruitment via social networking applications yielded a sample of 5511 cisgender SMM aged 18-85 (M = 38.21, SD = 12.16) who were in a relationship with an adult cisgender male main partner. Respondents completed an online survey assessing their own cannabis use, illicit drug use, and condomless anal sex (CAS) with casual partners during the past 30 days as well as their belief about their partner's engagement in these behaviors. Three subscales of the Perceived Relationship Quality Components (PRQC) scale assessed relationship quality. Across the observed range of PRQC scores participants who reported their partner used cannabis, used other illicit drugs, and had recent CAS with a casual partner were more likely to report engaging in these activities themselves. Among participants who indicated their partner did not engage in these activities, relationship quality was negatively associated with personal cannabis use (OR = 0.985, p < 0.001), illicit drug use (OR = 0.973, p < 0.001), and CAS with casual partners (OR = 0.979, p < 0.001); meanwhile, among those who reported their partner engaged in these behaviors - relationship quality was positively associated with the odds of these behaviors (OR = 1.018, p < 0.001; OR = 1.015, p < 0.001; OR = 1.019, p = 0.015 for cannabis, illicit drug use and CAS with casual partners respectively). These findings suggest that perceptions of a partner's behavior contextualize associations between relationship quality and personal behavioral risk. Results emphasize the importance of integrating components that support relationship quality into behavioral health interventions for SMM couples and SMM in relationships.