Midieval civil unions existed

Science Daily
August 25, 2007
In late medieval France, the term affrèrement -- roughly translated as brotherment -- was used to refer to a certain type of legal contract, which also existed elsewhere in Mediterranean Europe. These documents provided the foundation for non-nuclear households of many types and shared many characteristics with marriage contracts, as legal writers at the time were well aware, according to Allan A. Tulchin (Shippensburg University). [link]