I'm always a bit suspicious about claims which seem to be superimposing a modern idea on the past, and I can't really find any decent source beyond Wikipedia's journalistic source (and I have no idea if that is valid because I cannot read Spanish, sadly), so I was wondering if this was a real event and if it actually was what we'd understand today as "marriage" or something else.
This article merely referenced a document indicating the marriage as being incorporated into an analysis piece which won an award. I would look for an English translation of the paper referenced in the article, “Amigos e sodomitas. A Configuración da homosexualidade na Idade Media,” by Carlos Callón, and see what that says about the document in question. You could see if the National Historic Archives in Madrid have any information in English about this marriage document as well.
I can look for it myself (and will in fact — this is quite interesting) and report back, but I’m away from my sources right now and won’t be able to get back to it for a day or two.