https://www.merriam-webster.com/wordplay/ah-romance-a-word-borne-to-english-on-the-breastplates-of-chivalry

A Latin adverb Romanice, a derivative of Romanus, emerges with the meaning “in the vernacular,” alluding to the languages that had developed out of Gallo-Romance, namely Old French and Old Occitan. What is spoken Romanice, or “in the vernacular,” is decidedly not Latin, which is what was spoken in the church and in most formal writing.

In Old French, the Latin Romanice is adapted as romans or romanz. The new word is a noun, and it refers not only to Old French itself but also to works composed in it. It’s the Middle Ages now, and the romans/romanz composed are often narratives written in verse and chronicling—what else?— the affections and adventures of gallant and honorable knights. Romans/romanz takes on a meaning referring specifically to metrical treatments of the love and times of the chivalrous, and the fate of the Modern English word romance is sealed: its close association with tales of love join it forever to love stories, both true and merely dreamt of.