She is not my girlfriend, and we haven't had sex or anything, but we went to the club, we were dancing, and she started kissing another guy, what should I do?, should I try to have sex with her? or just completely ignore here?

Just so you can understand better, the guy was also hanging out with us, but the truth is she got out with ME, not with him, so I was being flexible in dancing with everybody I thought she had common sense and stop him when he got too flirty, but I go out for a second and go back and found them kissing each other......