considering the fact you said you "like" each other I'm going to come from the assumption that you're not a couple at this point. I agree with others that if the mutual attraction has been made apparent by you both, that it says a lot about him if he'd flirt with other girls in front of you but it also begs the question if there is a mutual attraction why has it not become a dating thing yet?

Can't really do much or say much about it if he's not your bf but.. it is a telling sign of the type of guy he is if he knows you like him and he did that.

Walk. Away. Plenty of guys out there that are more loyal to their gf or even their prospective mates.