From the girl's point of view:
I knew several girls when I was in grades 9 and 10 who were dating older guys -- much older guys. Christine was 14 when she starting dating a 22 year old. Granted, she led a very fucked up life, but she still did it. By the time she was 16 she had had threesomes and everything, but she was still dating the same guy. Katie dated a 21 year old when she was 16. The other Christine didn't "date" per se, but sure did get around, if you know what I mean. She got into clubs all the time with that gambit. The rest of us straight-and-narrow girls knew it wasn't quite right, but we didn't think it was illegal or anything. Just that the guys shouldn't be dating someone that much younger, and the girls should't be trying to grow up so fast. But of course we were all jealous about the sexual adventures.
I guess my point is that messing around with a 16 year old girl isn't neccessarily corrupting some young catholic schoolgirl (see hentai movies for reference). Many girls by that age are quite ready to be sexually active, and are searching out males who are mature enough to turn them on, and often 16 year old males are too shy and/or absorbed in skating/drugs/cars to take notice.