What are some misconceptions about monogamy?

Nikipedia asked a Q about benefits of monogamy and it was mentioned that misconceptions about monogamy are baffling. Can anyone provide me with any particular ones that you have found having to deal with? This is for all people, regardless of whether or not you’re in a monogamous relationship or in a relationship at all. This is not a question where people can bash either polyamory or monogamy, thanks!

I also want to know where these misconceptions come from most often. Who are the people that hold misconceptions about this relationship norm in our society?