I think you need to mind your own business here. The #1 comment is worried about fucking up the 13 yr old. Shit doesn't happen like that. Sure, there are some people that date younger partners because it allows them leverage in the relationship. This would be toxic but that's not necessarily why your friend is dating a younger girl. Then, there are people that start dating when they are really young because they naturally gravitate to imbalanced relationships. Those people needed help before getting into any relationships with anyone so we can't blame the elder partner for fucking them up.

When I was in my twenties, I started dating a girl. She looked young, but she was very sexy. She assured me she was legal age and I even met her mom! Anyway, as time went on, things didn't make sense. I find out that she was 15 AND that her bf before me was actually older than me. She had misled him too. As it turned out, she had a whole bunch of issues that led to drug abuse and emotional problems. Dating older men was a symptom, not a catalyst, of her issues.

Yet, I've also met plenty of long term couples that started dating older people at a young age. This Saturday, I'll be spending time with a good friend. She is in her early 30s. She started dating her husband when she was 16 and he was 31. I also worked with two females that each met their husbands when they were underage and the guy was in his 30s or 40s. Completely well-adjusted people. I think its just as ignorant to look at age gaps as inherently unhealthy as it is to look at interracial or homosexual the same way.