It helps to throw yourself into some activity that occupies your mind while you recover.
Obviously you have given this person your heart and I am guessing you feel as if there is no answers or closure.<br />
Just ask youyrself this question, if you go back to him/her, would that person change??
Then if you know that it is over, what is stopping you from letting go??
I do get it. When I seperated from my first wife, she had screwed me up so much I didn't know who I was.
The way I changed and moved on was being positive in what i did and thought. write down a plan and work out what you want to do. Make sure all the elements in your plan are positive.
Surround yourself with positive people.
The other thing i did was write down what I did wrong in the relationshipo, and what I should have done. This helps you clarify and organise your emotions. Use your support network around you and do positive things.
Thats the way to transition out of your thinking.
Its because you still miss him and it takes time to move on!.
You may think you dont, but a part of you just cant let go yet. Time is the best healer. Hang in there :)