What does it mean if a guy doesn't flirt back when I'm flirting in spite of the fact that he is fond of flirting?

Unfortunately that sends the message to you that he is not interested.

it means he dont like you or doesnt want a girlfriend or just wants to be mates.girl i hate to say it but it could mean that you be really bothering him. i do that to a guy that flirts with me and puts his arm around me and holds my stomach and i is really annoying so maybe you should stop flirting and try something else that us teens do to get a guy make him jealues or something or just get over it!!!

-He's annoyed, so leave him alone. He doesn't like you; if he did he would at least make an attempt to flirt back. Don't keep trying, guys HATE girls who can't get a clue and have to tell them too back off. This, in turn, makes the guy look like a jerk so they will often say nothing or humor you to spare your feelings.