In a thread i wrote a long time ago i wrote that my stepfather used to project the problems he had with my mother onto me. He would tell me what MY problems were in front of her and then correct them.
They oddly enough turned out to be exactly the same problems as my mother had
My mother "understood" this many years later and then she did the same thing to/about him.
If she fully understood it i don`t know? But she would be very strict with me when she saw i was behaving badly in the same way as my stepfather did.
Yet when my stepfather did the same he got away with sympathy for his difficult job situation or that he needed time to calm down.
But he never got that "15 year loathing" for something he had done, she normally put THAT under the carpets before the dinner was served.