"Life without Fathers or Husbands" by Clifford Geertz is an interessting essay that describes the social organization in a Chinese tribal group: the Na.
At a first glance, I remained kind of stunned while reading the essay.The Na don't have this institution called "marriage" which stuck people to be together until the end. Indeed, the Na share not only the person who they love but also their own children. Both men and women can as many partners as they want. Nothing is forced, any Na has the right to choose whoever they want to have a relation with. The men usually goes to "visit" the women or even more than 1 by night. By having a specific code to tell the other person that she is choosen for tonight, the suggestion remains open until the person has accepted it.
Moreover, since the Na share their partrners and they don't have a matrimonial relationship, they don't know what is jealousy. It is their culture to do so, therefore there is no reason for them to be jealous or to create issue about it. I thought at the beginning that it was kind of weird. By having a european culture where even if you are not married it is not used to have multiple partrner and even less to share them.
However, I enjoyed the part concerning jealousy. I think that divorce exists because being jealous in a couple leads to destruction.
Nonetheless, this essay shows us that marriage is not an universal instituion, nor nuclear family.