It beggers belief that a teenage girl would not tell her girlfriends about an overly aggressive boy immediately after the event, even if they weren't best friends for ever. Every woman knows that as well as men with sisters. Word of such gets spread very quickly on the girl-telegraph...phones would have been buzzing all week end..." Did you hear what happened to..." Her shrink must have been raised in a alt-feminazi cave to to not question the account.
I went to parties, when I was in high school, and I bet that everyone else, here, did too. It wasn't just girls who talked about them later; boys did too. And my parents would ask if I had had a good time, who was there, etc.; it was just what "normal" people did.