Many people make themselves intensely miserable because they don't know how to break up once and for all. It so happens that I'm witnessing several such stories around me at this moment. Instead of ending a profoundly unhappy relationship once and for all, people keep going in endless circles, arguing, fighting, crying, and making both themselves and their former partners completely miserable.
Then, there are also those who are into "remaining friends" with their former partners and spouses. It's possible that there are cases when such "friendships" are healthy and don't serve the purpose of manipulating the next romantic partner into permanent submission, but I'm yet to see them. More often than not, such relationships are not about friendship at all. They are about people trying to make themselves feel more important at the expense of new partners.
I always warned everybody I ever dated that if the relationship were to end, it would end completely. After we are done, we don't get in touch any more in any way, form, or manner. And I also reserve the right to forget the names and faces of each and all former partners. As a result, today I don't have to drag around the useless baggage of failed relationships and marriages.