My issue is that it's like we have 12-13 chapters of constant build up of Tifa and Cloud and their dynamic and relationship. Then suddenly we have 1 last chapter where we get 1 single dialogue line between them which is the complete opposite to Aerith where I think she did absolutely nothing for about 5/6 of the journey in Rebirth only to force the player to do shit with her at the very end
I don't think it works at all well and her character ends up looking really shallow because of it
It's jarring because it's supposed to be, it feels wrong by design. The devs went out of their way to be less ambiguous - and it really does not get any more overt than a kiss - about who Cloud likes but also about who Aerith really likes as well, and by the end it's hard to argue much in favour of the answer being each other.
But let's take a step back. Quite often I see people on the outside ask a simple question that gets somewhat overlooked by veterans of the franchise - "Why does Aerith like Cloud?" - what's really being asked here is, "why in a hypothetical situation would either of them actually have romantic feelings for each other?"
The reality for most neutral observers is that Cloud and Aerith barely get time to know each other. In the two short weeks of awareness of each other's existence, the priority is Sephiroth, saving the world and shlepping Johnny's sorry ass out of trouble. Further, in the moments they do seem to spend together, Cloud isn't particularly nice to Aerith. In Remake and Rebirth he's both dismissive and even rude to her, yet she keeps trying. But why?
Ah, but you'll say, Cloud acts a bit of a dick to everyone and you're not so far off the truth. He's bigging up his tough guy, SOLDIER fantasy persona and really the only time (and this is straight from the devs) that he ever really is able to connect with his normal self is when he talks to Tifa - as an aside, there's a good foreshadowing here of the Lifestream sequence and Tifa's centrality to it.
But that only even more begs the question, why is Aerith even remotely bothered with him? She doesn't have the past connection that Tifa does, she doesn't know the real Cloud even if she is aware of his facade and he doesn't exactly endear himself to her during their short time together.
The answer is Zack. No, not just at the beginning, but in the middle and at the end too. Aerith cannot get over him, she still loves him, pines for him and waits for him. But yet here there is an all-too-similar guy that so happens to arrive into her life in exactly the same manner with the same eyes and the same sword. She relates to him in the way she would relate to Zack, feeding him the same energy that Zack would have bounced back, only to hit a brick wall in Cloud's inability to reciprocate.
She tries and tries until the Sector 5 Dream Date, the moment of clarity and resolution for her character ahead of said character exiting the stage.
All her attempts to recreate that relationship with Zack are brought to a head here and the answer of her own subconscious, her own dream, is that "it's not right because it's not what I want." - as we said before, it's meant to feel wrong. NPCs commenting how they don't look like a couple, Aerith not getting the things she wanted, Cloud unable to treat the moment as anything more than friends hanging out, Aerith admitting her feelings for Cloud are ultimately not so clear cut.
This doesn't step on the toes of two full games of CT build up, it only comes to rubber stamp it. There exists not even a modicum of the romantic tension that is present when Cloud is with Tifa, when with Aerith instead. He cares about her, no doubt, but he made his choice many, many years before she even knew he existed.
Aerith, for her part, would be shown to be a bad faith actor to both Cloud and Tifa knowing their mutual affection yet pursuing him regardless - but now that we know he was merely a stand-in for Zack it can be rationalised as nothing so insidious, but rather the desperate attempts of an exceedingly lonely girl to recreate a lost love.
