In fandom slang, a romantic pairing that fans support is called a ship.
The term is derived from “relationship” and can describe a pairing of fictional characters or real people whom fans want to see together. Fans may support a ship through fan fiction, fan art, discussion, edits, or speculation, whether or not the relationship is officially part of the story.
The relationship sense of “ship” is generally traced to online fans of The X-Files around 1995. Supporters of a Mulder-and-Scully romance helped establish the terminology, although the broader practice of imagining relationships predates that usage. “Shipping” refers to the activity or phenomenon, while a “shipper” is a person strongly invested in a pairing.
A pairing confirmed by the source material may be called a canon ship. A fan’s favorite pairing is often called an OTP, meaning “one true pairing.” Pairings can also be named by combining characters’ names, such as “Reylo” for Rey and Kylo Ren. “Macro,” “tag,” and “thread” are fandom-related terms, but none means a supported romantic pairing.