I was in a similar situation but I was the one getting into the bars...and of course the long distance thing-he left for college. And on the weekends hed call and Id be out-and call til I got home-3am or whatever. JEALOUSY was there because he knew guys would be hitting on me...HOWEVER we had trust amongst us-no problems.
Let me give you one word of advice-if you know shes going out-DONT badger her about it-if shes going with her girlfriends-dont worry. If she truly loves you she wont do anything to jeopardize your relationship. She'll be smart off to tell the other guys to go to hell or be friendly and tell them she has a boyfriend.
Dont make a federal case out of this-if you guys already made the arrangements and or plans to continue to stay together while shes at college then relax. Right now youre feeling a little insecure about it all but as time goes on-you'll see if youre relationship can withhold the distance. But always keep your lines of communication open-and the trust factor there!
I spent 3 years in that situation and never cheated on him or vice versa. Its how you feel about that person and how much youre willing to give to the relationship and her.
If you feel that the trust issue is going to be a problem talk to her but be prepared for some back lash from her-she'll get defensive about it, doesnt mean shes guilty, shes at a new place new friends, new experiences, allow that for her to grow, and you do the same for yourself.
If you feel in your heart you cant continue this because youre scared or insecure then you should evaluate what it is you want for yourself...you dont want to spend this time always worrying about her and other guys it WILL make you physically sick and mentally messed up.
Goodluck-
everything happens for a reason...beginning to wonder why.