I actually really enjoy the idea behind this battle fuck mechanic. Essentially, you're momentarily trading tempo in hopes of cashing in with big attacks the turn after for greater gains. Solid!
If I may make a suggestion though, I feel like this mechanic would benefit from more predictability, or from some way to influence how the enemy groping attacks shake out. I often find myself in situations where one of my characters with a move that needs Sexual Resistance to be used gets down to like, 20 or 30 SR, which is too low to actually use the move, but still quite a ways off from getting reduced to 0 and getting assaulted, especially when you take to account the passive SR gain from getting kills with base attacks. This makes the SR moves quite difficult to rely on, in my experience.
Taken this, perhaps some way to manipulate SR more directly could be considered? Taking a turn to masturbate for +SR for example, or maybe some way to 'present' to particular enemies if you're at low enough SR to have them target that girl with a grope attack with like a bonus to the SR damage they deal with that attack? This taunt idea I think would be a better fit, since it more fits the core battlefield manipulation gameplay loop of this game and lets you use the extant porn content more deliberately to your advantage. For example, use Taunt on an enemy you think you can finish off with the other characters to get them to assault you, use resulting SR refill + Afterglow to clean house.
Anyways, still really liking what's here so far!