My parents ostensibly chose each other, but it's really more like my mother preyed upon my father. He's a bit younger than her, not as educated, was shy and not overly ambitious, and perfect for her campaign of modeling someone into what she wanted. My aunt says he used to have a great group of buddies back in the 60s when they met, and one by one she weeded them out of his life and replaced them with people she thinks had higher social status. This tape has recycled itself routinely throughout their lives as she discards someone and finds someone new to glom onto for a while and try and be them. She has him totally under her thumb, and she's a vicious monster who regards other humans like furniture she rearranges.
People didn't know much about borderline personality disorder in the 60s when they met, and he's too shy and unable to defend himself, and while they do squabble, she always wins. He has very little insight into how toxic she is, and goes along with all her psychotic shit, like how nobody can use a bathmat and you can just slip and slide on the wet floor, or how you can't keep the toaster or kettle on the counter and have to put it immediately back in the cupboard burning hot, because her narcissism means everything has to look like a museum.
He dated some woman before her, just a girl really, who was chubby I guess, and my mother spent one dinner with extended family joyfully insulting this woman, who he last laid eyes upon probably 40 years prior, and asking him repeatedly with vicious gleeful delight if he remembered "the ball", meaning this chubby girl. My spouse wanted to clock her in the teeth. We were all just kind of numb to her behavior then and tried to ignore it, but not long after I awoke to who she really was and haven't seen them since. It's sad, but she regards me as a piece of lost property really, and I don't think there's a good enough therapist in the world to wake him up to how dangerous she is.