Please find sources to support your claims. Science established that humans are polygamous by nature so your claim is false. What I advocate for is openly talking about it and set the rules ahead of time. Most people don’t do that our of fear and when most people have an affair they then keep it to themselves.
Our society and its social norms steer people in that direction. Cheating is not naive, it’s an urge. Some cultures and religions, including Mormons in the States, practice polygamy. Unfortunately, only for men, which a sexists abomination.