In this new three-part series Louis Theroux explores how some Americans are dealing with love, birth and death.
His first ‘poly’ family are Heidi and Jerry, who opened up their marriage 12 years ago. He goes with them on a date night as Heidi’s new fiancé Joe joins the family, leaving behind his wife and two kids.
We also meet Joelle, Marilyn, pregnant AJ and father-to-be Mattias, who all live together (see main picture, above, clockwise from top left).
A baffled Louis struggles to comprehend why no one is jealous or resentful.
Please note this programme airs in Northern Ireland at 10.30pm.