Why is Monogamy Idealized When Most People Aren't Monogamous?

"According to the animal kingdom, and research with creatures from insects and fish to birds, apes, lions, tigers and bears (oh my), monogamy is exceedingly uncommon in the natural world. In fact, with advances in the technology of genetic testing, many of the species previously lauded as being lifelong monogamous, are now known to actually have many sexual encounters outside their seemingly monogamous partnerships. While they may maintain long-term pair bonds with a single partner, they do not maintain sexual fidelity. Swans, geese, and eagles, species long romantically described as monogamous, have now been revealed to have engaged in nonmonogamous sexual activity in as many as one out of four births. In fact, according to some researchers, it’s more newsworthy when evidence of monogamy and sexual fidelity is actually supported in the animal kingdom."