Why am i not good enough?

Ok world here it is in a nutshell. im 19 and ive been talking to the same boi since i was 12 years old. A few months ago I broke up with him because he thought that a relationship wasnt the best thing for him at the moment. Well as of now we are best friends and nobody knows him better, he hasnt found anyone that has treated him like I have yet he's constantly looking...why? What does it take? Im not trying to be mean or rude but i look at his preference in boys and i look so much better than them and i treat him so much better than they do. We're so close i swear i can hear his thoughts sometimes. We've even slept together since we've broken up. I'm just confused. I was enough before, and now we love each other more and we're closer than we've ever been. Why am i not good enough now? I've been there for him through absolutely everything why would he want somebody else? What am i supposed to do?