This study explores the affective dimensions of female sex workers' relationships with their intimate, non-commercial partners and assesses how emotions shape each partner's sexual and drug-related risk within their relationship. We draw on qualitative data from a study of HIV, sexually transmitted infections and high-risk behaviours among female sex workers and their non-commercial partners in Tijuana and Ciudad Juárez, Mexico, to illustrate that these couples share relationships based on love, trust, respect and emotional and material support. These relationships range in emotional intensity, which shapes partners' decisions not to use condoms with each other. Drugs were important in most couples' relationships. Among injectors, syringe sharing was common and represented both a sign of care and a pragmatic reaction to conditions of material scarcity. Our findings suggest that couple-based HIV interventions to address dual sexual and drug-related risks should be tailored to the emotional dynamics of sex workers' intimate relationships.