Being in love is a lot of fun, and I know what it's like to feel your heart racing every time the person is within a hundred yards of you. I know the nervousness and the emotional overload. It seems like you'll have a great day so long as you just get to see the person, even at a distance.
But neither you nor I can know the future, no matter how intense your feelings or hopes may be with regard to a particular guy. For example, I was madly in love with a girl when I was a senior in high school, and she was all that I could ever imagine or dream of. Because I had never experienced such intense emotions and attractions before, I confused infatuation with destiny. But it wasn't meant to be. About a decade later, I met my wife.
At the age of fifteen, you're not really supposed to know if he is "the one." Focus on your friendship with this guy for now, because that will be the best foundation for a lasting love (if that is to come). Be patient and keep things pure. You won't regret it.