My Girlfriend has a crush on another guy... What should i do.?

we are in a long distance relation ship, which is hard all on its own... but now i find out she has a crush on someone she meet through me. I found out because she filled out a dumb survey on myspace and on of the quetions was "do you have a crush." i asked her if she just meant me and she said yes... but later that night she IMs me on aim and said she lied. Now she ended up talking to the guy and she told him but said she "loves me and never would leave me"... so the guy tells her he likes her too. I just dont know what to do...