Two key points.
This is NOT Polygamy.
Polyamory is growing in the Millennial to 30ish age group.
They view it as a modified FWB with the added emotional connection.
Also women seem to be more supportive of it than men.
Right - promiscuity dressed up with the phrase “in love”.
When his rebellious son Absalom had sex with his father's concubines, that did not go over well with King David.
King David was a polyamorophobe.