This really makes no sense. Laziness or "stubbornness" doesn't even begin to cover it. So they just never dated other people? Or they dated and slept with other people EVEN THOUGH THEY WERE MARRIED? This never was a problem for them? EVER?
In the novel, she frequently mentions how "if anyone else had treated her like that" she would have packed her bags. If it's abusive asshole behaviour from a stranger - it's still abusive asshole behaviour from your husband.