Was allegedly assaulted then walked the few miles back home. Why didn't she call the parents to come pick her up? Why didn't she tell her parents of the assault?
I'd think she was afraid of getting in trouble for going to such a party. And if some sort of attempted assault by someone did occur, she might not have been thinking too clearly.
OTOH, that (6-8 miles) is a long walk, especially after having gone swimming. 2 hrs., at least, I would say. And even back then and in I assume "good neighborhoods", for a girl, alone? Who at the party did she like enough to do that? No party ever motivated me that much, that's for sure. (Getting stranded w/o a vehicle did once, though.)