It seems crazy, but sometimes the WAS seems compelled to re enact their childhood trauma. My ex left just when our kids were the same age he was when his mom left.
My xh has married someone (not the original OW) who is very like his mother . . . . The original OW was like the crazy version. He never sorted it out when she was alive. From where I am sitting the dynamic of the relationship is much more like the one with his mother. Not at all like the relationship we had.