I wish you wrote more on this topic as i actually found it interesting.

The sunk cost effect is particularly true especially if the couples would lose everything in the long run. Sometimes Love is the least of most peoples worries, their real estate, cars, houses is enough motivation to want to keep living together.

In addition to your post, i am sure, their chidren is another reason most couples keep living together. Culture is naother big reason, i am from Africa where divorced couples irresective of their reasons for divorce are seen as failures, the society stigma is usually much and bad....,

keep writing