Anybody can be friends but both partners have to be motivated and the ability to be receptive to changing such a relationship. It takes time and attention to really make this transition. You may see that this can work but if it doesn't then it is best to let it go. He may not be receptive for many reasons. In the end they are not important. What is important is that he wants to move on. You can't be the only one interested in being friends. Most times people do not remain friends. There is too much history and the feelings just can't make this transition. For some people it is just too painful or they are too angry. I would let him have his peace and move on. You have to respect his wishes and he is more typical of a couple that doesn't work.
If this is helpful press accept