Why this girl try to steal your guy?

She likes him. Not hard to see.

She could be trying to make you jealous because she wants what you have, if the guy is right for you he wont pay any attention to her. cool right

No... This ^ is wrong. See, to understand how a GUY'S mind works... He wants to be popular and have a hot girlfriend, along with some other things... Few, if ANY, males, will have the strength to resist a girl, even if they don't like them that much. I'm a guy. I should know. I will admit, I have been swayed in such a way, and broke a heart. So... WHATEVER YOU DO, DO NOT LET THEM STEAL YOUR GUY.