He has a girlfriend but is he interested?

Ok well...my best friend is dating this boy. and yeah all three of us are friends.well when she isnt around like in our homeroom at school he looks at me and stares a lil bit. i have to say he is kinda cute but im not getting involved with my bestfriends man. but he always teases me .i know he really likes my friend and she really likes him. he told me he liked me when they broke up one time but then he went out with my friend and i just dont know :/