Their throuple was in an open relationship, allowing them to see other people.
Their throuple was part of a polyamorous relationship, where all partners were romantically involved with each other.
Their throuple was a committed partnership, dedicated to supporting each other through thick and thin.
Their throuple formed a non-traditional family unit, raising children together and sharing household responsibilities.
Their throuple was seen as a modern relationship, challenging traditional notions of monogamy.