Wonder why it took 3 years to report the abuse.
That is a good question. Who knows. Usually these things come to a head when the individual wishes to form his or her own relationship outside of the inappropriate one. It also may have arisen from counseling sessions where some other behavior or emotional/mental issue was connected. Regardless he was 13 and it was wrong on both counts. There is no justification for sexually predatory behavior of an adult with a 13 year old. Even if he was gung-ho about it a child can not make those decisions and it is a responsibility of the the adults in question to protect the under-aged child.
They (the two women) weren’t showing the same level of attention he was use to receiving??
I expect it took him 3 years to decide he didn't like it anymore.
It isn’t abuse if you go willingly. Something tells me the kid liked it, at least enough to keep quiet about it for 3 years.