I'm surely not the poster boy of doing it right, but, I do know that I was terribly co-dependent and once I grew past that, I didn't miss her so badly. I think a lot of the time detaching is about becoming whole. So, if that is part of your relationship, that's a place to focus your personal growth. Then, onto practical matters. The more time you spend not doing something, the more time you have to stew and miss your W.
I think we'd all need more details in order to give more specific advice.
