I asked myself that question a few days ago, well we all know the obvious reason, but never never did the psycho tell me why it failed - lets see now oh now I remember - "I cant do this anymore" was a comment he made a few weeks before it was over - mmmmm cant do WHAT anymore? ACT? is that what you "cant do anymore" ??? But never never was there a logical narrative on his part - "you are too needy, "its just not working for me anymore", "you have too many issues of insecurity", those seem to be the popular explanations they give when they get bored and want to move on to other supply and new enablers - If you stop and remember what their reasons were for wanting out and ending it, it had absolutely NOTHING to do with what a real loving relationship is all about, and there is a reason for that - because it was never a real loving relationship to begin with.
I will always remember that "I CANT DO THIS ANYMORE" - thats because your facade, persona and con is up with me - so move on to someone else who will believe it as I once did - go put on a shiny new mask and go be a different person to someone else - that is what all your relationships are - of course it ends when you simply "CANT DO IT ANYMORE"