The current study will conduct a randomized controlled trial (RCT) to test the efficacy of 2GETHER, a novel couples-based intervention for young men who have sex with men (YMSM) that aims to reduce HIV transmission risk by optimizing relationship functioning. The investigators will conduct an RCT with 200 dyads (total individual N=400), who will be randomized to receive the 2GETHER intervention or an attention-matched couples-based positive affect promotion program.