How to know if a guy likes you?

There's this guy who flirts with me more and touches me more than he does with other girls, BUT he is a huge flirt, however all my girlfriends assume that he likes me more. One of my closes friends said "if something were to go wrong and awkward with u two, then i don't think he and i will ever talk" and replied back saying "why" she said "because whenever we talk its always bout you" APPARENTLY he talks to other girls about me. BUT i found out he likes this other girl who has now left the school, but who lives in the same city....urgh idk