Dating younger guys?

I have feelings for a guy who is a year younger than me, and I think he might have feelings for me. If we start dating, it would probably be next (school) year, where there's an odd maturity gap, where he's at the age where guys are really sexually promiscuous but they're not 100% ready to be in a sexual relationship, but it's appropriate for girls my age to be in a sexual relationship. I know if a relationship between us lasted, it would be a situation where he wants to have sex, and it goes against my personal beliefs to let him lose his virginity at such a young age of it isn't going to be special. What should I do if I have to reject him to have sex? Or how should I go about it so he doesn't regret anything that happens?