Most Helpful Guy
It's hard to move on from something like that specially if you weren't give the proper answers you probably needed to hear or deserved. All you can do is distract yourself from whatever means to forget about him and that includes hanging out with your friends more, going to the gym more often and trying out new activities. You have to fully cut whatever connection or ties with him in order to properly move on with your life, otherwise you'll keep thinking or him and probably wanting him back. It will take time, but that's all you can really do to forget about someone.
Most Helpful Girl
Maybe it's best that you don't know the reason. Leave it be and seek your own closure. Perhaps you were just too good for him to begin with.. I mean that might be staying the obvious here. After 3 years I would think that you would at least deserve that respect.