Louis Theroux: Altered States - Love Without Limits

Love and marriage. Do they still go together like a horse and carriage - or is the model no longer fit for purpose? British filmmaker Louis Theroux visits 'US capital of polyamory' - Portland, Oregon - to meet the couples opening up their relationships in eye-opening ways. For many, more partners means more love and happiness - but for some, he finds, it means jealousy, upset and broken hearts.