My H(33), just found out his sister (19) is dating a 45yo man. H keeps threatening to go find this dude and well, you get the picture. But IDK what he thinks he can do! She's technically an adult, living on her own, her parents have not been there for her since she was 8. I really feel like shes trying to fix her daddy issues with an older man. It's extremely concerning, but what can you even do about it? We don't even know this guy or where they live, and my inlaws refuse to get involved or tell her that she could be unsafe.