It’s easy to see why a divorce law might arise that allows men relatively easy divorce, as in the Old Testament which lets men divorce almost at will (as written, interpretations differ) but gives women no right to divorce at all. It is also easy to see why a society might adopt mutual consent under which both parties must agree in order to get a divorce or no-fault unilateral rules in which either party can get a divorce without the consent of the other. What is difficult to understand, however, is why a society would adopt divorce laws that make it difficult to get a divorce even when both parties want a divorce. Who benefits from such rules? And yet this was the common situation in England and the United States up until say the end of the 19th century. In England, for example, it took an Act of Parliament to get a divorce. One might argue that such rules benefit children but aside from the questionability of the premise this view would also have to answer how it is that children have political power?
Hat tip to Sasha Volokh for bringing the question to mind with an apropos quote on divorce from a 19th century British judge.