I think there is a fine line in Rebirth between Romantic and Platonic and the writing and depiction of both Cloud and Tifa and Cloud and Aerith's storylines do different things when it comes to the line
Strictly Romantic - Cloud x Tifa
The Line/Middle Ground - Cloud x Aerith
Strictly Platonic
What I mean by this is that there are multiple moments in Rebirth that can't be considered anything but Romantic, a nearly kiss, confirmation of "mutual feelings" in the moment, staring at them with a smile on your face whilst they aren't looking and an actual kiss between Cloud and Tifa - as well as more - are moments that can't be misconstrued, aint nobody going to believe these are things you just do with someone if they are your strictly your friend. These are things you cannot just back up on now in Part 3, because people will start to question will hang on, you had Cloud and Tifa nearly kiss, as well as kiss (even if you say dates are non canon the general public won't see it that way) and then you just dump all that like they didn't happen just to make Cloud kiss/end up with Aerith at the end, what? That would be terrible storywriting and characterisation especially with what we know are big moments coming up between the two in Part 3.
However with Cloud and Aerith I feel like they straddle the line between Romantic and Platonic enough to the point there is no moment between them that I feel like "there is a point of no return now" depicting friendly interactions between them or Cloud being upset at her death is not Romantic, and things like the hand holding and "dates" can be considered romantic obviously but then others interpret them as comforting or platonic depending on the context, or even related to Zack and Aerith's memories of him (S5 date, depending on how you interpret this, i'd love the Directors commentary on this scene) Then of course there is the one sided confession from Aerith where she herself is conflicted on if she even likes Cloud romantically or platonically, you cannot get more middle ground if you tried. It would seem to me she'd like to have the opportunity to know which way she likes Cloud but never gets said opportunity for obvious reasons.
Being an adult about this, I would like to think as adult characters the so called "elephants in the room" aka peoples feelings are addressed in Part 3, namely;
Zack and Aerith's reunion - They need to resolve the idea whether Aerith "like likes" Cloud because that is the impression Zack seems to be under due to Marlene's comments, not to mention Aerith herself wrestling with the idea on if she does or not, there's no way they don't address this.
Real Cloud and Tifa's reunion - The Lifestream is a perfect moment to - again - brandish the mutual feelings between both characters, however this time both Cloud and Tifa are already closer than ever and their relationship is way more developed at this point than it ever was in the OG, meaning the Lifestream has potential to be even more heart wrenching and romantic between the two.. hell, could we see an honest to god confession here from someone?
Real Cloud and Aerith meeting - I think this will happen yes, I think it will because if they want everyone to have a happy ending I think he will meet Zack and Aerith one last time to have a real conversation in order for him to move forward with his life. IF this were to happen i'd like to see them address the idea of a romance between them and if anything could have happened, and I think what should be said for closure for both of them is that, maybe in another lifetime, if Zack and Tifa never existed and Aerith wasn't tied down by destiny, who knows, but that never happened, and Zack and Tifa do exist and the reality is Cloud and Aerith have only ever loved both of them in that way respectively and they are both with the person they truly want to be with, but they part ways still loving each other as friends/family with Aerith still watching over Cloud and Tifa and everyone else. Is this cheesy as hell and unrealistic? Yeah but.. I think it would be a nice thing to cap the whole thing off of.