<human>: I've been in a relationship with my girlfriend (18/f) since high school.  After going to different colleges, I transferred to her college to be with her.  I know that this is generally a bad idea.  We are at the end of our first semester together and currently making summer plans.  Several weeks ago we both agreed to work at a summer camp far away from where we live.  At the time the camp was my best option, but I wanted to wait to see if anything better came up.  I never told her that I was holding out for a better opportunity.  Now, roughly a month and a half later, I have an opportunity to stay home for the summer and go to nationals with my city's U-19 ultimate team.  This is the last year that I am eligible to play, and I would regret it for the rest of my life if I didn't take this.

My girlfriend is very hurt.  She had chosen this camp over another based on the fact that I told her I would go with her.  She says that if I don't go to camp with her, that it will take her a long time to get over this, and that her trust in me will be permanently shaken.  In her mind, I should keep my promise to her even if it means missing out on something I will never be able to do again.

My problem is that I agree with her.  I think that I am being selfish, and that our relationship would get along much better if I just went with her because I said I would.  However, I also feel that at my age I can't afford to miss out on opportunities that I would pounce on if I were single, just because I'm in a relationship.  I want to play ultimate, chase this dream, and then deal with the consequences later.

Can you summarize the given text in a few sentences?
<bot>: My girlfriend wants me to go to summer camp with her, but a new opportunity has come up for me and I want to take it.  She doesn't like that at all.  What to do?