I have a great relationship with my nephew; he confides pretty much everything to me. When he first had a beer, when he lost his virginity, normal teenage stuff, and every time, it seemed to me like he's been safe (no drunk driving, wore a condom, etc.)
One thing about him is that he doesnt look his age (he looks like he's 22-23 at least), he’s tall and athletic (football player type), so the guy is quite handsome.
The issue is that a few days ago, he told me he's been seriously dating a college girl (23) and he's all excited about it, but doesnt want to tell his parents or the family until he turns 18 (he turned 17 last month). I don't know anything about this girl. He met her at some party, and he says she's super sweet and they're equally into each other. I know the age difference isn't huge, but I worry about legal issues. I don't even know the law on that, but I feel like that's a no-no.
I told him this whole situation was complicated and that he should maybe cool things down and wait until he is legal to avoid complications. He said that, in his case, he is the underage one and the girl is the older one, so it doesnt matter the way it would if it were reversed. I tried to explain that I don't see it that way. But he dismissed me and still asked me not to say a thing.
I probably screwed up for not telling on him about the other stuff that seemed like normal teenager stuff (I did the same things back in the day), but I feel like, for this, I should tell someone…WIBTA if I tell my sister and my BIL? Should I just stay quiet? We live in a small town, so I doubt they'll be able to keep it a secret for long anyway.