Distance makes the heart grow...more distant.
I recently left home (and my boyfriend of 2 years) for college. I know that I love him, but at the moment I don't really miss him and he is a 14 hour drive away. I haven't cheated on him, and I have no intentions of doing so, but I'm meeting a lot of new and interesting people and there are a few that I wouldn't mind getting to know a little more intimately. We promised to tell each other everything, but I've kept my loss of feelings for him a secret. I don't want to lose him, but I feel like I'm missing out on a little of the college experience.
You are in college and experiencing new things. Most high school relationships don't survive that kind of separation. Odds are he is feeling the same way.
You sound like a stupid **.
It happens. You realize that stagnant high school relationships mostly happened because you didn't know new people. Now you do, and they are fresh and exciting. This happens a million times.