Amazing thread... this thread just made my day, but lets cut the bullshit seriously. No body on this forum knows ur gf better then you do. Your the man, you need to evaluate the situation and act with what your gut feeling tells you. Assess the situation and make a decision. In YOUR opinion, based on what you have seen so far, what do YOU think?
Whats her personality like? any values? Good family? well raised? How does she treat you? etc... now based on these factors, the chances of her cheating on you are very slim, it DOESN'T mean she wont tho. You also need to evaluate her friends and their background, which is usually a big FAIL.
My advice to you is let her go, instead of telling her (take care of ur self baby. I trust you baby etc..) Tell her, go have fun, enjoy it, party a lot. YOU should be HAPPY that shes leaving and make her feel that. You gotta confuse her and before she leaves. do your self a favor and fuk her brains out.
Your the man, your in control, step it up, fuks her brains out and wish her good luck.
Now statistically speaking, she is more likely to cheat on you. I can almost guarantee you that she will and you will never find out.
Do what you have to do, go out have fun , bang some chicks while shes gone and dont feel guilty.