She was only 15. It’s possible that she went to a gathering, and she got in a bad situation, probably with someone else. To justify her bad behavior, in her mind she built a false narrative where she was a victim. (just another possibility)
I will probably be flamed for this honest assessment.
She went upstairs to use the bathroom, presumably because two-story homes don’t have downstairs bathrooms.
Either that or she was drunk and flirting/fooling around with the boys when she realized she had allowed things to progress too far and started to scream. The boy she was petting with covered her mouth until she shut up. Perhaps the boy was Kavanaugh.
Fast-forward a few decades and she sees an opportunity to resist Trump, so she destroys Kavanaugh’s reputation with a malicious twisting of the facts.