Guys, Why do unhappy people stay?

I recently had a conversation with my friend he opened up on he's marriage about he's wife of 6 years (she is also a friend but I met her through him) he told me she moans about the things he enjoys in life like watching or playing football, meeting with friends alone, disagrees on pretty much nearly every decision to do with their two children, he quoted "I am always in her bad books" I have been out a few times with them on couple dates (me and my boyfriend, my friend and he's wife) and have noticed she likes to make fun of him, he would be telling a story and she would say things like oh no that didn't happen and laugh, basically belittling him, he also says he has tons of washing, ironing, cleaning and looking after the kids to do while she goes out which he said he wasn't too happy about (he did say he doesn't mind helping out with chores) but she has so much more freedom than him, My question is why do nice genuine people stay in unhappy marriages? Is this common? I hope when I get married it won't be that bitter, I don't understand why he stays I really don't I just wouldn't say this to him.
5 d
He also said she is very argumentative.
Guys, Why do unhappy people stay?
Add Opinion