I have a friend who I met at work that I used to do everything with (camping, mtb'ing, hiking, fishing, hunting, RMEF projects, carpool, he babysat my kids). We even bought our first bows and had them set up at the same archery shop. We both killed our first archery elk (his first elk ever) on the same weekend which included an epic packout. In that same area the next year he said something to the effect of, "This is my favorite thing to do all year." (referring to backpack archery elk hunting). That was almost 10 years ago and it was the last time we hunted together. Even writing this is painful. He went through a rough divorce, and a few years later his Dad committed suicide. I thought hunting would be a good way for him to get away from it all, but he just gave it up. We finally "had it out" a couple years ago after my frustration finally reached its limit. We cried and hugged it out (super uncomfortable for macho guys like us), but it didn't exactly close the rift between us. We still work together and get along ok and occasionally go on bike rides or help each other with little projects, but it's a much more casual relationship - I never depend on him for anything because I cannot deal with the disappointment when he cancels or flakes out.
Like someone else said, you have to hold onto the good memories and let the other crap go or it will eat you up.