This paper uses a life-course approach to explore the sexual partnerships and HIV-related risk of men and women in Swaziland throughout their adolescence, their 20s and 30s. Twenty-eight Swazi men and women between the ages of 20 and 39 discussed their life histories in 117 in-depth interviews, with an average follow-up of 9 months. Many participants reported painful childhood experiences, including a lack of positive role models for couple relationships. Women’s first sexual partnerships often involved coercion or force and resulted in pregnancy and abandonment by partners, leaving women economically vulnerable. Most men and women reported a desire to marry and associated marriage with respectability and monogamy. Men typically did not feel ready to marry until their 30s, while women often married only after years in tumultuous relationships. A high degree of relationship instability and change was observed over the study period, with half of participants reporting concurrency within their primary relationship. Participants’ narratives revealed significant sources and circumstances of risk, particularly multiple and concurrent sexual partnerships, violence, and lack of mutual trust within relationships, as well as social ideals which may provide opportunities for effective HIV prevention.