I think it's more likely that pretending that monogamy is important and then in reality having a culture where cheating is rampant is the actual problem. In other words, it's the lack of ethics that is the actual issue. There are all sorts of cultures around the world where strict sexual monogamy is not expected (even though they have pair bonding) that do just fine. Pre-patriarchy, humans didn't practice strict sexual monogamy and that was for 97% of human history. How did we get that far without monogamy as a core value if it's so critical?
I may have to give this book a look-see because it seems to me that a culture where people are free to be who they are without social mores enacted by others to constrain their lives would be much more functional in all ways. Humans are social creatures used to bonding and affirming connection in all sorts of ways, including via sex. It's only with relatively modern patriarchal demands, which come not only with the social and sexual control of women but an entire system of classes and hierarchy that free sexuality becomes any sort of an issue. When you have cultures that believe in caring for the wellbeing of all children, it hardly matters who the father is. That's the real issue, I think - we don't have a society that is invested in the wellbeing of the larger group.
“And yet, partible paternity, where several men have sex with a woman and are considered the father of her child is a long-standing practice in many parts of the world and a far from rare dynamic. Polyandry was normal in pre-contact Polynesia, particularly for high caste women and still takes place in the Indian Himalayas and in parts of Tibet. In Lowland South America, and in Africa partible paternity, where two or more men mate with a woman for the purposes of producing a child, is common in many cultures. Spreading fatherly feelings throughout the group helps to maintain solidarity and cohesion as well as promotes the wellbeing of a greater number of children. Reproductive fitness (the chance that offspring will, in turn, produce their own offspring) is enhanced by cooperative alloparenting of this kind where several adults take an active interest in the lives of children.”
The difference is that in these cultures, non-monogamy is being done openly and honestly rather than on the DL. There are almost no animals that have true sexual monogamy, and even in human cultures where the punishment is death for failing to maintain it, it still exists quite widely. That doesn’t seem to align with this author’s premise, but I am interested to learn more about him just out of curiousity.