You could even hit the whole parenting thing head on & let parents in on the action. Could be very successful in certain places. I hear China is resurrecting arranged marriages in a modern form.
Hence the market opportunity: a social site for kids/adolescents -- or security tool for same -- that ensures that users are the ages they say they are, and only allows close-in-age interactions. In fact, there is already at least one angel-funded startup working on this very concept. They work with schools to confirm user identities and ages:
http://www.thefrankpetersshow.com/2008/07/eguardian_protects...
TCA deal lead Steve Block liked what he heard about eGuardian before they even presented! He had another company that was dealing with children online. Steve would put the two companies together and bring the critical focus to transform eGuardian.
Attorneys General from 49 states are pressuring social networking sites to protect kids. eGuardian partners Ron Zayas and Robert Patrick have a new approach to protecting children while they're online.
Which isn't what they've built. It seems like maybe you're after a different business entirely. It might be a good business, but I don't think it's the one the OP is trying to build.
Another point about market opportunity: some high-school and college students go to same-sex institutions (which might be a good idea, since it minimizes distraction, and hence could become more popular over time).
The only problem with this idea is that it's dangerous. The reputation of the Internet is that of a haven for pedo predators...you make a dating site for 14 year olds (or even allow them on your site) and you will bring down the wrath of every Sarah Palin-loving soccer mom in America (i.e. the really dumb ones, who believe it when Oprah tells them that pedophiles are organized, after their children, and have over 9000 penises).
Besides that, kids from high school through college already have tremendous dating-related interactions at school. They're not short of new people to hit on and flirt with. I just don't think it's a very good market to go after, even if it wasn't a death wish from a legal and political perspective.
But, it should be kept fun, distinctly non-sleazy, and light. I've always been totally turned off by the "Find your soul mate, who has passed our credit check and has a valid US ID.