How do I handle this situation delicately?

I have been trying to figure out what to do about this for a while, but I have resigned to the fact that I could use some help, prefereably from a more neutral source.

I am 17, turning 18 in July. I am a senior in high school and will be going away to college next year about 1,000 miles away from home.

My girlfriend (who is just 2 months younger than me, but a junior) and I have been going out for 6 months now. We have very good communication, and we can talk about EVERYTHING. I know you are probably thinking of typical teen "communication," but we actually do talk about the important things and have discussed feelings, physical boundaries, and much more.

We are both mature and really like each other, but what worries me is that I am her first real boyfriend.

My first serious relationship was about a year ago and gave me a crash-course in a lot of the aspects of dating, including the infatuation/love boundary.

I recognize that I like my girlfriend a lot, but I do not think she is "the one" and I understand that realistically we are never going to be married.

She, on the other hand, has fallen into the same wild infatuation that I would classify as first "love." Though we have discussed it and I have told her that I do not anticipate this being a very long-term thing, she is convinced that we will be together for a long time despite her insistence that she is just "living in the moment."

As college approaches, I have been getting more and more anxious about what to do.

On one hand, I know that long-distance relationships are not only extremely tasking, but unlikely to succeed and I do not wish to be together for too much longer.

But on the other hand, I do not want to hurt her and I would rather not go off to college with a girlfriend still at home. I respect her a lot and I know I would never do anything to cheat on her while I am away.

I know that the worst thing to do is to lead her on and give false hope, but I have done everything I can to try to convince her we need to be realistic and she still remains naively hopeful. As my mother noted, "when they fall for me, they fall hard."

At this point I do not know what would be the best course of action, let alone what to say to her that would let her down easy as well get the point across.

My plan of late has been to stay together for the first bit of college to show her how hard it would be not seeing each other for weeks on end, then try to break up when I come back for winter break.

Please help me find a way to handle this effectively and maturely in a way that would cause her as little pain as possible.

Sincerely,
~Speechless