True, not many people would want to live with their ex, unless it's a really amicable split. However, you can't always find someone else who just happened to got divorced, can't afford to live on their own, and is in search of a roommate. Plus, who moves out? Maybe their house is better than their roommate's.
If they're just roommates, they don't really need to deal with each other's personalities, and not even habits if they set some rules. Such as - clean up after yourself, divide the house into your own territories that you can do whatever in, split the fridge etc. So they don't really need to deal with each other too much. They no longer have to clean up after one another, argue on decorating styles, what to eat, or deal with each other's mood swings and such. So all in all, it's still a better solution.
It is quite strange that the man would be naked though knowing that his ex-wife would be coming back and they're no longer involved.