Once society abandons the traditional definition of marriage and redefines it to mean any two people who love each other and want to get "married," there isn't any logical reason to limit it to two people and prohibit polygamy and polyamory.
If you read the Supreme Court's decision overturning sodomy laws, you could switch homosexual relations and insert polyamorous relations and every argument reads the same. Scalia said this would lead to a slippery slope and he was right.
Once society abandons the traditional definition of marriage and redefines it to mean any two people who love each other and want to get "married," there isn't any logical reason to limit it to two people and prohibit polygamy and polyamory.The author concludes her article with "The definition of marriage is plastic."
The Left's goal is the Smash the Patriarchy and Smash Monogamy. Ending the institution of marriage is the name of the game. Make it meaningless.