More at https://www.philosophytalk.org/shows/polyamory.

In most if not all modern Western societies, monogamy is the dominant form of romantic relationship. In polyamorous or "open" relationships, however, each person is free to love multiple partners at once. Just as our friendships are non-exclusive, advocates of polyamory believe our romantic relationship should be too. So why do so many people find polyamory distacteful, or even despicable? Is it immoral to love more than one person at a time? Or is our society's commitment to monogamy simply a fossil of tradition that could one day be obsolete? The Philosophers welcome back Carrie Jenkins from the University of British Columbia, author of "What Love Is: And What It Could Be."