I don't blame you for wanting some kind of explanation. Anyone would want to have at least that much consideration from the one who simply walks away with no words.
During the past six months, I know you have thought this over and over again, and nothing we say seems to help, (which I wish there was something we could do). I remember you being told that even if she had given just one explanation, it would not have made any difference (even though you think it would have). You would have gotten worked up over that one answer and argued or tried to talk her out of the decision. I thought that was the best answer that had been given to you on this subject. Truth is, whatever she would have said, you would have spent the last six months stewing over her answer.....b/c you have to get through this time frame (how ever long that may be) in order to get over the shock and pain.
You are right about one thing....you didn't deserve the way she left you. Since you have never given her reason to fear you physically, she is either chose the manner of leaving b/c it was her idea of being the "easiest way" to end things, or she planned it that way b/c she intended to avoid any resistance from you. It still gives no reason as to why she left, and that's what you really wish to know.
Some day she may decide to tell you, but in the meantime, I believe you need to accept the fact that she may never give you any explanation. Now, I realize you have a hard time accepting it, and may not understand it....but it might actually be best for you that you don't know her reasons. Her reasons could be a lot more upsetting than dealing with what you don't know.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!