The game's bugged in many places right now. Main character is not supposed to have a lewdness rating higher than 60 whilst still a virgin, however repeated use of the dildo at the nurse's office will jack up the score and make her lose virginity anyway.
As I mentioned before, the easiest way to unlock the scenes is to do a virgin clear. The bug with enemy attacks actually makes this easier since you're allowed to close a gap and smack an opponent around until your MP runs out.