Welcome to the world of confusion and chaos that comes with entering the dating game. We all experience highs and lows when we get excited, and then our potential partner somehow drifts away.
You'll soon learn that a disappointment is just a bump in the road. I think you should let it go and get on with your life. There will be lots of other guys you like in the future, and lots of other guys who like you and stay with you (for weeks, or months, or years), and maybe even one who stays with you forever. But neither of you are likely to be mature enough to make a relationship last for long when you're still in school. So you've lost a 'dream' right now, not a life partner.
Put it in perspective, and you'll see this little disappointment isn't worth any tears or heartbreak. I suggest you just move on with your life and see what the future brings.