It is also difficult for me to believe anyone stays monogamous for reasons other than fear and insecurity. However, humans are also *lazy* and busy earning money, and doing things to achieve status. A "monogamous" relationship is one part of a public life that makes someone an upstanding citizen. Some people are scared into doing the right thing, others are simply putting on a front, and others truly believe and want to do the idealized picture because it feels rewarding.

Also, even though cheating is rampant, how frequent is it? Once per year, once per month? Under what circumstances? (Only when the relationship has instability, or to prove there can be another lover /romance for long periods of time?)

I wonder if more people cheat at lonely/unstable times in their relationships, then polyamory - other lovers at stable times would seem destabilizing even if it is not the intent.