Bubbe, my grandmother, did not approve of the women her sons married; she did not consider them good enough for her family. Clearly, nobody could be. But her daughter's husband, my father, was her special nemesis.
He had a lot of charm, but it was lost on her. They loathed each other from the getgo. When he tried to mollify her, she was not playing, and their mutual hatred grew worse.
Mother always felt that you could please two people at once, even if they wanted completely opposed actions on her part. This worked about as well as you would imagine it would, which is not at all.
After my grandfather died, it was generally agreed that someone would have to move in with bubbe. The whole family felt that it should be my mother, her only daughter. So the three of us moved in with her.
The result was a clash of wills, and since bubbe was twice as cunning as my father, she won the long game, thereby destroying our family and depriving her grandchildren of a father. That was collateral damage, and didn't matter, as dad was obviously a weak character and we were better off without him. Bubbe was as compassionate as Julius Caesar, who surrounded his enemies and starved them all.
The tradition continues: my nephew just got married, and his sisters hate his new wife and think she's not good enough for him. Fortunately the young couple are moving out of the country, so perhaps their marriage has a chance.