What do you do when someone confesses their love to you and you like them back but your to young for dating?

Here is what you do:

You learn how to spell "too" correctly. And you also learn grammar; "someone" is singular, you can't say "them" and "there" about a "someone".

In addressing your question specifically, I think you answered it yourself. You said you are too young to date. Just be very good friends with that person.

But you are probably not going to like my answer since I offended you by fixing your English. ;)