I can likely sum up the story once all of the facts come out:
The uncle is a perv.
The girlfriend is a slut.
The boyfriend cant choose women.
But she cries rape when her boyfriend catches them in bed, the boyfriend beats up the uncle....and the police arrest the uncle for....something. Boyfriend takes it out on the uncle for not being smart enough to see this coming from a mile away.
The perils of young women, and all that. I had it explained to me by a co-worker many years ago.