@Cyberus
That would probably be a borderline case, and up to the parents in that matter.
I got together with my gf, who was 21 at the time, when I was barely 17. I have a 24 year-old friend, who is seeing a girl that he met when she was 17. No complaints from parents there.
It basically depends on your ethnical background, and wether you have a well-paid job or not :\ (I am
so going to get flamed for that! :-P).