Long distance relationships can work out -- I was involved in one for 2 1/2 years (12 years ago) with the woman who became my wife. I live in Virginia and she lived in Michigan - a good 12-13 hr trip one way.
The keys are: visit as often as you can afford (and make the visits, say, a week if you can -- I was lucky enough to be able to do this), keep the path of communication open and frequent, and, most importantly, get to know the other person inside and out (mentally and emotionally, I mean). Either one of you will be moving a long way to be with this other person day in and day out, so trust your instincts.
I've now been with my wife for 10+ years, and it has worked out perfectly for us. That is not a guarantee that every relationship will work out, but if it is meant to be, you'll know it.
Duane