In order to be completely happy we have to be able to completely let go of the things that we know will never be again. We have to let go of our pasts, and the memories that bring us down. Looking back will only hold us back from progressing forward, and while it is ok to be thankful for the memories that make us smile, if they are attached to someone that brings us a lot of pain when we remember them then maybe we should try to limit those memories from arising as much.

Staying away from these memories takes a lot of effort and mind control of our thoughts. Try to occupy your time with a hobby or a passion of yours that makes you think of things other than the pain that one person may have brought you. It will take a concerted effort and usually a lot of time, but with a strong will and a strong mind getting over your past will free you forever.