Sure thing, Lir.  Basically, it's got different levels of arousal and climax, both physical and mental, each having a set DC for Prowess checks to get your partner to that level.  Honestly?  I think it's a bit of a pain, and tends to break the mood when you're rolling every post.  If you'd rather ignore it, and keep the intimacies to pure roleplay when there's no NPCs involved, it's fine with me.