Usually if you are talking to a guy and another one is staring unhappily at that guy it's either one of three reasons. One he likes you. Two kind of ties into one he cares for you but doesn't trust either you or the guy so he's making sure you two aren't flirting. Or three he just flat out doesn't like that guy and it has absolutely nothing to do about you.
BECAUSE THE GUY MIGHT LIKE THE OTHER GUY!!
Let me answer your question with another question ... why would someone look at a painting in a museum if they already have a completely different painting at home?
He has a crush on you!
He likes you.
Either the guy is interested in that girl, or he just was interested in what she was saying.
it means he like you or he's into u give it a shot
if a guy you stare at stares back and then his friends do then that means most likely he likes you he may like you but he could also be talking about you to his friends.
It means he need to see a physician. He needs to get a life!
He is shy around you! He likes you a lot but to scared to say anything.
Most likely
He probably thinks you are beautiful,as all girls are.
He probably likes you too
i would think it means hes jealous and doesnt approve of you talking to another guy
he liks her
maybe hes in to you