https://quillette.com/2018/06/07/explaining-monogamy-vox/
The show itself seemed to suggest that since our closest primate relatives engage in polyamorous free love it's likely that we do as well. This can be further supported by observation of hunter-gatherer tribes, or so they argued.
The author had a different take. He didn't necessarily suggest that monogamy was necessarily the norm nor was it natural. However, he also didn't believe that humans naturally gravitate towards egalitarian polyamorous societies. Instead, the norm tends to be polygeny, societies where the upper echelons of men have more wives, while the lower-rung of men simply don't marry or are forced to share. Indeed, a good way of garnering loyalty if you're a higher-status male was to share your wives with your inferiors. Many of the very hunter-gatherer tribes mentioned in the Vox video were themselves polygynous rather than egalitarian polyamorous societies, and frankly quite misogynistic.
To be clear, wife-sharing isn't polyandrous (one wife many husbands). The difference is that the wife doesn't get the final say and probably doesn't even have a choice. These societies are polygynous. Polyandry is rare and often occurs in certain environments, or so the author suggests.
Monogamy came about likely because those societies that embraced it had less sexual competition. They were less violent. More cooperative. Societies that didn't embrace it were easily subjugated by the societies that did. Progress is not the norm in polygynous societies.
Frankly, between a polygynous future where you're either being stabbed in the back or doing the back-stabbing, or a future where a software glitch causes a world-ending exchange of nuclear weapons, I'd pick the nuclear exchange. At least the latter is over in an instant.