What's a song about him being "the one" but you can't be together?

This guy and I met 4 years ago and it was truly love at first sight..but we were both seeing other people at the time.. and every time we tried to get together it never worked.. but we always say how we'll end up with each other in the end and how we're going to get married so we should date around and have fun but in the future it will end up being just me and him. another factor into this never being together thing.. is the fact he now goes to school across the country so i barely get to see him and we have to resort through texting/phone calls/ims.. ect. so what's a good song i could dedicate to him?