It is so hard, you want things to be like they were, but usually, it just doesn't work that way.
Think about it this way - why do you yearn for someone who doesn't want to be with you? Take yourself out of the situation, just like he did.
Try your best to keep busy, to move on, to get on with life. Fill up your time, volunteer, mentor a child, work with the big sisters organization, drive for meals on wheels, visit a nursing home, work extra, go back to school or take more classes, make time for friends, or make new friends. Do something to help yourself move forward - work on being a good person - do someone a favor without asking - eat some ice cream
or whatever makes you feel good!
Do not dwell on the past - it is over and you need to make a new future.
Good luck!