@gailcalled That’s a fun list, but there is no other English word for many of the items on it, and others have connotations that the English word doesn’t. So no, we don’t use fiancé for the same reasons (read the original question).
It’s weird: the French word has become the normal word. If you use the plain Anglo-Saxon betrothed instead of the French, you might sound pedantic or pretentious, and if you use the Latin-derived intended, you might sound like a country bumpkin. It’s all backwards.
I was talking about word origins in a college class a while back, and some of my students said they had never heard the word betrothed or even seen it in print.