we have only been going out for a month. but everything has gone perfectly. and he says he wants to spend the rest of his life with me. but how do i know he is serious other than his words? body language? his eyes? how do i know for sure?
Hopefully you are old enough to make this decision, affecting you both for the rest of your life.
If you are under 20, slow down, or at least wait a year before you get engaged, then married, then have kids.
Space things out, huh?