Why does a confident outgoing guy get jealous whenever he sees you talking to any of your guy friends and look or stare at you almost every time when he sees you in class or in the hallway?

Well the number 1 thing is he might have a crush on you and you just don't realize it. and if your crush has a crush on you heck yeah he will get jealous. and there his friends hes ether telling them about you or he trust them maybe you should make friends with his friends and find out why his is so jealous.