Aerith was supposed to be this Japanese strong and pure woman in the original. Every translation took liberties, she's really forward about liking Cloud in the English original, I vaguely recall. ("I bet you'd like seeing me and Tifa in swimsuits!") It's meant to be a side effect of her innocence and sheltered upbringing. As well as the whole not quite human deal she's got going on. They went for the innocent angle on the remake, like when she's super hyped for cross dressing Cloud. They also play a lot with how the rough bartending brawler who does ecoterrorism as a side gig is the bashful one who treats Cloud with kiddy gloves, and the modestly dressed florist is pretty much willing to jump him in any dark alley.
She falls for him almost instantly because he reminds her of Zack. Aerith being an Ancient, there's this whole probably supernatural element to her love for Zack and then Cloud. My take on it is that it's supposed to be a love so deep it transcends even death and instantly recognizes Zack in Cloud... But really does come across as just horny pretty often.
In the end, all of the love triangle is just there for misdirection, I feel. It all plays into how Tifa was treating Cloud carefully because he came back with Zack's personality. She's even flabbergasted if you have Cloud flirt with her in the original. Aerith is super into him because she feels Zack in there. And then Aerith dies, Cloud un-Zackifies himself and his true personality comes out and Tifa starts getting a lot closer to him.
Even if it hangs out over a big part of the game, in the end it holds very little importance.
As for 7R going to be a Golden Ending, well yeah. Looking at past FFs, X was a fucking camp trip to Miseryville, and X-2 was a rainbow colored HOLY FUCK RIKKU IS ALL GROWN UP pew pew let's watch Brother kill things by ramming into them ass first Charlie's Angels ripoff. With great music and a shitty completion system. That rewarded you with a golden ending. Even that had some emotional impact, since it was really hard to do and you got to bring Tidus back. Bringing back a game that ended on a bittersweet note 20 years ago and not giving it a super happy ending would feel out of character for Squeenix. Even more so with how long it's gonna take them to do the whole thing.
That said, when Zack gets to eat Sephiroth sword or when Gackt lethally snipes him with a mako-infused apple or whatever, it'll still hold some emotional weight. Of course, this Cloud seems a little bit more Cloud than Zacloud, so he might just be alive and well. Aerith biting it seems incredibly unlikely purely on the grounds of it being a long, grindy game and losing that sort of progress is gonna prompt some strongly worded letters arriving at Squeenix. People probably don't remember, but the last game that pulled this was Metal Gear Solid V and the backlash over Quiet's death was so crazy strong, they ended up patching in a way to get her back, canon be fucked. At most, they'd have someone inherit her stats.