As far as I can remember, didn't a couple have a bunch of adopted children, one of whom told mummy that daddy/stepdaddy did things to her in the attic. So, the child was pretty much locked up for life, to treat her mental illness, for saying such a thing.
Later, another one of the adopted daughters became married to daddy/stepdaddy, and it was ok because it was not really a relative, and it was a pure and innocent love story between a barely legal girl and an elderly man/stepdaddy.
Nobody seems to have joined the dots and wondered if the marriage of the second daughter/ stepdaughter to daddy/ stepdaddy might suggest that the first daughter was not lying, about the man, and should never have been locked up for telling the truth about his activities with her in the attic
Old men, or their ex- child -brides, may tend to have personal reasons to convince themselves there is nothing amiss with whoever wants whatever contact with underage girls.