Just caught up with this thread and wanted to comment that I'm glad your friend is choosing to move on and cut off any further attempts at communication. I was also the victim of a "disappearing boyfriend". In his case I know for sure he was going through a tough time after the sudden passing of his father (it happened while we were still on good terms), but it still wasn't a good excuse for how he treated me. Like John he did the fade out, calls and texts would be fewer and farther between and he suddenly had such a hectic work schedule he couldn't get together. I was always understanding and put up with a lot more than I should have because he was grieving, so of course he just needed some space. Eventually he stopped returning my calls altogether. I regret to say that I did end up sending him a letter and in retrospect I wish I hadn't, but at the time I was hurt and felt like I need some closure. I never did hear anything more from him, but I met a great guy two years later who is now my DH and we have a beautiful little boy.
The best revenge is living well IMO. Good luck to your friend, she is better off without him.