BACKGROUND: HIV treatment-based prevention modalities present new opportunities for women to make decisions around sex, intimacy, and prevention. The Universal test and treat (UTT) strategy, where widespread HIV testing is implemented and all people with HIV can access treatment, has the potential to change how sex is understood and HIV prevention incorporated into sexual relationships. We use the frame of sexual scripting to explore how women attribute meaning to sex relative to UTT in an HIV prevention trial setting. Exploring women's sexual narratives, we explored how HIV prevention feature in the sexual scripts for women who had access to UTT in South Africa (prior to treatment guideline changes) and increased HIV prevention messaging, compared to places without widespread access to HIV testing and immediate access to treatment. METHODS: We employed a two-phased thematic analysis to explore longitudinal qualitative data collected from 71 women (18-35 years old) between 2016 and 2018 as part of an HIV prevention trial in the Western Cape Province, South Africa. Of the participants, 58/71 (82%) were from intervention communities while 13/71 (18%) lived in control communities without access to UTT. Twenty participants self-disclosed that they were living with HIV. RESULTS: We found no narrative differences between women who had access to UTT and those who did not. HIV and HIV prevention, including treatment-based prevention modalities, were largely absent from women's thinking about sex. In their scripts, women idealised romantic sex, positioned sex as 'about relationships', and described risky sex as 'other'. When women were confronted by HIV risk (for example, when a partner disclosed his HIV-positive status) this created a point of disjuncture between this new perception of risk and their accepted relationship scripts. CONCLUSION: These findings suggest that HIV-negative women did not include their partners' use of antiretroviral therapy in their sexual partnership choices. For these women, the preventive benefits of UTT are experienced passively-through community-wide viral suppression-rather than through their own behaviour change explicitly related to the availability of treatment as prevention. We propose that prevention-based modalities should be made available and supported and framed as an intervention to promote relationship well-being.