Medieval France and elsewhere in pre-modern Europe

Same-sex unions were not unheard of throughout medieval Europe. Source: Medieval Lists
A 2007 report in the Journal of Modern History showed that same-sex couples in medieval France could enter the legal entity of affrèrement, or brotherment/twinning, meaning that they shared a household, property, and life. Although the contract sometimes referred exclusively to siblings, the report also noted that on occasions these shared-household contracts also referred to unrelated pairings. These unions were strictly secular, not religious. In the agreement, both parties became each others’ heir. The practice has been documented to exist elsewhere in Europe, especially in Mediterranean countries.
Similar agreements were performed throughout pre-modern Europe, and some had religious components. As writer and lawyer Eric Berkowitz has written:
“In the period up to roughly the thirteenth century, male bonding ceremonies were performed in churches all over the Mediterranean. These unions were sanctified by priests with many of the same prayers and rituals used to join men and women in marriage. The ceremonies stressed love and personal commitment over procreation, but… [c]ouples who joined themselves in such rituals most likely had sex as much (or as little) as their heterosexual counterparts.”
Much has been written about how these unions were more of a domestic-partnership than a same-sex “marriage,” so it’s hard to definitively say that same-sex marriage was commonplace throughout medieval Europe.
Based on this example and the others in this list, however, history makes clear that with regard to partnerships, the “traditional” can mean more than just one man and one woman.