I was just chortling about that quote on the previous page from Fox about the query that Aeris and Cloud could have been a couple if things had been different and there was no Tifa.
Beauty is, the Cleris angle NEEDS Tifa and Cloud's devotion to her (or is it faith in her?) to substantiate their fantasy. They need Cloud to have gone to Shira to impress Tifa, they need Cloud to have met Zack, and to be emulating Zack's mannerisms and traits to create that precious chemistry that "might" have sparked a relationship if it hadn't been for those things that, erm, created that chemistry. And also of course, if Tifa hadn't been around, Cloud would never have gone to Shinra, probably died in Nibelheim, Zack wouldn't have necessarily died protecting Cloud on the trip back, might have made it back to Midgar, and lived on with Aeris... gah, fails that way too! Aeris ends with Zack.
Of course I'm being flippant, fiction is bendable in any direction - but my point stands is the precious chemistry between Cloud and Aeris is a side-effect of their personal legacies to Tifa and Zack respectively (or the other way round for some shippers...). It sucks, but on the face of it, Cleris is nothing but a fantasy with no way to really ground it in the FF7 lore without major, major revisions that change the characters we know and love.