I can understand and sort of related to it to be honest. For me, once i put my intense shipping goggle on, I can never take it off… This happens to me for Bleach, where I think Ichigo X Rukia is the main couple, and got slapped in the face at the end…i re-read the manga lately, and still think ichigo x rukia are cute together….anyways, I guess the difference is some people like me are not so fixate on the idea of being canon, and can accept that other ship is the canon ship, which doesn’t stop me from enjoying my ship at all….there are so many fanart honestly. But for some people, being canon is a big deal, and apparently it doesn’t worth the time and money if their ship is not canon.
EDIT: maybe they just got really attached to Cloud X Aerith in the early game, and will ignore all the hint and development for Tifa in the later half of the game…it probably will only get worse if someone hold on to the idea that cloud X Aerith is the canon couple for 27 years. I don’t think anyone will be able to convince them they are not