This may be so, but it's because they don't realize all the ways that they are swimming in patriarchal norms and uphold them as well. Patriarchy is a social system (it's not a synonym for men). This particular social system is only about 6-9 thousand years old. What we call traditional marriage is absolutely a function of patriarchy and it informs much of the way that partners in that relationship style tend to related to each other. Prior to the rise of patriarchy, relationships were not based in control, they were not based in the man being the head of the family. In fact, sexual exclusivity wasn't expected because there was no way to enforce it (without the social controls of women that came with patriarchy). In addition, the primary survival strategy is the entire tribe or enclave all taking care of each other so it hardly matters at that time who the father of a child is. That only becomes important with patriarchy - a few thousand years ago.
There are cultures throughout time and all over the world even today that do not believe in sexual exclusivity. Impulses towards jealousy are perhaps human nature, but the extremes that are normalized in our culture today are absolutely a function of a belief in ownership. In other words, they are a function of patriarchy.
"Many of the relationships that are characterized as marriage in other cultures look nothing at all like the concept we have of that institution. Words like marriage, mating, and love are socially constructed phenomena that are culture-specific and have little or no transferable meaning outside of that culture. Ritualized group sex, mate-swapping, unrestrained casual affairs, and socially sanctioned sequential sex are all reported in cultures that some anthropologists may characterize as monogamous simply because they’ve determined that something that is referred to as “marriage” takes place there. Even today, there is a lot of investment in relationship styles that make sense to us by Western standards and fit our norms."
“Despite the belief that monogamous male-female bonding is how mothers and children were supported and thrived, the anthropologist Sarah Blaffer Hrdy and others believe it was actually female cooperative breeding, or alloparenting — ‘sharing and caring derived from the pooled energy’ of a network of ‘grandparents, aunts, uncles, siblings, distantly related kin, and non-kin’ — that shaped our evolution.” (2)
In most of rural Africa children wander in and out of the homes of unrelated adults in their villages, where they are treated as family. This stems from a more community-oriented lifestyle in general, but also from a lack of concern for parentage because sexual exclusivity is not prioritized. In fact, in some cultures, it is considered downright stingy."
"Partible paternity, where several men have sex with a woman and are considered the father of her child is a long-standing practice in some parts of the world and a far from rare dynamic even today. Spreading fatherly feelings throughout the group helps to maintain solidarity and cohesion as well as promotes the well-being of a greater number of children."
You may feel that monogamy is a choice but the culture as a whole does not — they believe that it is the only correct way for humans to be in relationships and anything else is still widely stigmatized, even as non-monogamy becomes more popular.
And imagining that other cultures all look at love, relationships, and sexual fidelity in mostly the same way that we do in our culture is a great misconception.
This is my academic area of expertise, and I realize that the layman may not have the same understanding of the terms that I use. Jim is a frequent reader and conversation partner, so I knew he knew what I meant. Here's a couple more stories I've written, should you be interested, about the social system of patriarchy which is somewhat distinct from the feminist use of that word.
