What in the world did I do

The old girlfriend is crazy and the ex-wife is nuts. I've heard this for every relationship of any guy I've ever known. With the exception of Demi Moore, we are all guilty of mental illness.
Alas, in my old age, I'm just figuring out that it's merely a short hand for men. It enables them explain away the person who was once part of their lives but is no longer and in such a way, that they feel okay about it and their current partner has no questions, until of course, she becomes the same. I was the crazy a few times, and yes indeed I really was, no holds barred, messed up but good. It's embarrassing on top of the heartbreaking time already in motion.
How come at times when I did the breaking up, no one was crazy, it was just the right time? Wherein I think it's the overlap that qualifies the classification, and men being the ones doing the defining are often about the intersection. I am never going to just nod again when I hear it, not that I'll argue lest I reveal how touched I actually am.