how do you know if a boy likes you? lol or if he just wants to have sex and then leave you?
simple. :) if he tries to have sex with you and then you say "I dont think we know each other well enough yet" and he breaks up with you, then you know he never really liked you.
and I think the key word your looking for is "love" not like. never have sex with someone you dont love. :)
They wait and don't rush into sex - if you don't have sex with him fast he'll leave you (if hes using you). Make the guy wait to see if he sticks around, if he starts pressuring you. dump him.