I fully understand it. My friend was my "best friend" (sounds odd saying that as mid-50s man), but we shared a real brotherly relationship. A combo of full-on-acceptance paired with complete honesty that siblings share....so when he died it felt very isolating.

About a month or so after he died I had a very very vivid dream concerning him. One of those dreams where you wake really feeling like you just had a real conversation with someone....in the dream we were both sitting on the floor smoking cigarettes talking (we had long each given up smoking in our late 30s but in the dream we were still smoking)....we were talking about his death...very matter-of-factly ...he looked at me, pointing his cigarette towards me to make a point and said "YOU have to let me go....you gotta stop dwelling on this and just move forward". I woke up instantly feeling like it was really something he would say....and in a strange sense it did help me move on. I felt like I got that "one final conversation in".