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.
If either side had wanted to get to the truth, that kind of investigating would've been done.
Part of the problem, I've hypothesized, is this really gets into the lives of the DC elite. A lot of them went to that collection of elite DC prep schools and/or Yale undergrad. They must be squirming about their HS and college social lives being part of their job prospects.