I recently attended a lunch where a former couple (of two men) introduced their third partner (also a man) as part of their 'thrupple'. It was not a term I had heard before but an arrangement that I certainly had. Someone suggested it was strange - a pejorative word - and I corrected them saying that it was unusual in this day but was not odd or strange.
What are we? English? Welsh? British? Are we bothered? Most of the time our "identity", national, religious or whatever, probably isn't at the top of our list of concerns. But sometimes circumstances come along which make us less secure in ourselves, less able to take our place in the world quite so much for granted.