Either that or a 'child' (in age only) who is wise beyond her years whom the parents "couldn't handle".
Either way, he should not have been sexually involved with her.
What some of the 'kids' out there have on their behavioural resumee by 15 would be enough to give you gray hair.
I used to foster and my last 15 year old was 10 times the work than the 5 year old that preceded her.....
Sadly, the reason the 15 year old was like she was-— was because of rotten parents.