Time frame: Baseline, after completion of the 12-week intervention (Month 3 or Week 12), and 3 months after completion of the 12-week intervention (Month 6)
Presence of chemsex will be measured by a validated questionnaire. Chemsex is defined as the use of any of the following psychoactive substances before or during sexual intercourse: ketamine, methamphetamine, cocaine, cannabis, ecstasy, Dormicum/Halcion/Erimin 5/nonprescription hypnotic drugs, heroin, cough suppressant (not for curing cough), amyl nitrite (popper), GHB/GBL, 5-methoxy-N, N-diisopropyltryptamine (Foxy), and mephedrone. Participants will be asked whether they had used any of the aforementioned psychoactive substances before or during sexual intercourse in the past 3 months at baseline, after completion of the 12-week intervention (Month 3 or Week 12), and 3 months after completion of the 12-week intervention (Month 6)