Generally speaking, an ex is an ex for a reason and it's usually a very good reason.
You haven't moved on because you don't want to.
Somewhere in the back of your mind you're still holding out for the possibility that you will get back together.
You view dating other women as nothing more than occupying
your time until you are reunited with your ex. Basically you are "sleep walking" through life.
Some people believe if they stop feeling pain it means the love they had wasn't real. They feel guilty if they find themselves laughing and having a good time.
Maybe you would do well to cut off all ties with your ex and not discuss her with any of your friends and family. You may even want to have a symbolic funeral for the relationship by burying a few items (photos, letters,...etc), have one last major cry and then go meet your friends for dinner, drinks, or a comedy movie.
At some point having a happy life is a choice you will have to make as well as giving yourself permission to experience again.