Guys and girls can be just friends.
Most of my friends are guys and I wouldn't date any of them.
Relax.
I agree that she shouldn't be hanging out alone with other guys. Whenever I feel really comfortable with a guy and I have a pretty good connection with him, I honestly don't even think about other guys..and I cant really look at other guys the same way. I usually don't even notice them. Doesn't sounds like she's that into you. All I can say is ask her if she would be mad at you if you started hanging out with other girls alone. If she says she wouldn't care she's lying. Start hanging out with some girls to show her how it feels and if she gets jealous tell her that's how you feel when she is with other guys.