Having the ring charged by having sex would be like the cheapest trope ever (in fact, I thought this idea was one of the first discarded ones as it sounds like the most obvious setting for a porn game). Also, it assumes having a good time with girls is doing a good deed, which would need an explanation since sex is not something they seem to need: Maddie needed a roof for the first night, Sadie needed a job, her mom needed some money, even Danny needed her tips, and all of them appreciate some kind words (I'm just stating the main choices that led to a ring's charge). Who needs sex, though? And, more importantly, it does not exactly solve the main problem: when and how do you fit those scenes in the current narrative?