This girl I like hangs out with another guy. Are they just friends?

I like this girl, but before I could do anything about her it was too late. Another guy got to her first. They hang out quite often (from what I hear), so I was ready to drop this crush I had on her. But...

Whenever I am around her, I'm always getting these positive signals like eye contact, blushing, etc. (One of my friends even mentioned how much she stares at me when I don't notice her).

So now I'm wondering if she is actually interested in me, and if she views the other guy she hangs out with as just a friend?
This girl I like hangs out with another guy. Are they just friends?
Post Opinion