Do you know the age of consent where he was brought up?
Because if he dated girls above the age, then there's no reason to complain. He could be four score years and seven and toothless as the declaration of independence and there'd be nothing to moan over.
It's a simple legal issue.
We may find it ugly. But people write their own laws and have no reason to complain when someone abides by them.
If I had a daughter, I might have beaten him to a pulp. But that's just me.