You moralist people a just plain crazy. Weren't you EVER young? Perhaps badmouse did the right thing, but honestly I don't think that it makes a difference either way. If the kid wants to get with this girl, he's going to, one way or another, that's how teenage boys are. He'd probably give an arm and a leg as long as his penis was happy.
In any case, relationships these days are f-ed up one way or another. Sex is so commonplace among youth, it doesn't matter if she's 14 or 21, its still gonna happen. The right idea is to teach your child about responsibility. If the boy learns the fundamentals; what's a healthy relationship, proper technique for birth control, prevention of STDs, and most importantly how to treat the opposite sex, he should be able to make his own choices. Once your kid hits 13, if you force him/her into something they do not like, they are just going to rebel. There's no stopping kids unless you lock them up and destroy their lives. Instead you have to be honest with them and teach them in order to TRUST them.
No, I'm not a parent, but I'm not very far removed from being a teenager. I know the other end of the spectrum, and overbearing parenting solves nothing.