&gt; I&#x27;m not against polygamy or polyandry<p>Pedantic, perhaps, but while its generally acceptable to use &quot;polygamy&quot; to mean &quot;polygyny&quot; when you aren&#x27;t discussing &quot;polyandry&quot; (because virtually all real-world polygamy is polygyny), if you are explicitly discussing both forms, its should be &quot;polygyny and polyandry&quot;, &quot;polygamy&quot; includes both.<p>&gt; On the other hand, we&#x27;ve long had a tradition of traditional married couples where the man keeps a mistress on the side, usually in secret (though secrets don&#x27;t tend to last very long).<p>Its really weird to call monogamous marriages &quot;traditional&quot; when comparing them to the polygynous marriages, since while the latter have fallen out of favor progressively in the last several centuries, they have quite a long tradition pretty much everywhere.<p>That said, its actually in many places a long tradition for kept mistresses, particularly of powerful men, to be fairly open.