18-on-14 is kinda messed up. That's a senior screwing a freshman, right when the differences in pubescent advancement are likely to be considerable. There was one guy in my high school who would only "date down" four grades like this and we all thought it was creepy and wrong; it turned out he was a closeted gay trying to "pass" but who couldn't convince girls who had already been involved with other guys before - he had to be in control and set expectations so they wouldn't question too much.
The younger girl probably did consent, and youth sex laws need a generous "Romeo and Juliet" escape hatch. But still, 18-on-14 is creepy.
"Don't think it hasn't been a little slice of heaven just because it hasn't!" --Bugs Bunny