Im 21 and at University. My girlfriend of 9 months from home went to see a band with work mates (who I know well as I met her at work). She got called backstage with the band with a friend and got so drunk that she kissed one of the guys in the band. This kissing happened for most of the night (3 or 4 occasions) in view of people from work. Only after the last time it happened did she tell the guy she had a boyfriend, at which point he left the club. She doesn't recall kissing him several times but remembers the last time it happened. She told me as soon as she left the club and has never betrayed my trust before. She is hurting just as much as I am. What do I do? She wants to leave for another country because of this because how much it will hurt both of us to be around the place it happened. I love her deeply and I know she feels the same way, as we had planned to go travelling when I finish uni this summer. Do I take her back? I know that I could never do anything like what she did, and that I will never seek revenge. She wants to get back together but doesn't want to punish me so understands if I can't do it. We are talking but everything is so different. I believe in time I can forgive her but I am young and maybe it will be best to end it now and move on.
Help.

If she is so willing to let you go it is because she wants to.
Let her do her thing and you do yours. There are other girls out there.
Forgive her and let her be.

My vote: take her back.
She was drinking, not out hunting for your replacement. She didn't get alone with him and go further than what everyone saw.
Embarrassing, but understandable and forgivable.
All couples need a bit of time with other people, even a little flirting, to keep the relationship from going stale. Maybe it was a wee bit too much, but not horrible.
Maybe you should get drunk with some friends and kiss another girl, just to experience the next day realization that it didn't mean anything and you can barely remember it.
Leave the country? Please, don't punish her with so much guilt.

She only wants to leave the country if I don't want to be with her because she says she would have nothing to stay for.

I know, I told her not to leave the country. I agree with what you say, however going out and doing the same is a little different because I will be seeking to do it, whereas she didn't do this. I don't think that will be a good idea.

I'm not understanding her wanting to leave the country over getting drunk and making out with someone. That sounds a bit drastic and dramatic unless something else went on.
I don't understanding getting so drunk you don't know what you're doing, but you know the girl I don't. I just would hope she stays away from alcohol she obviously can't handle it.