I can understand how a player could think that Cloud and Aerith would've probably been together if she hadn't died. That English commercial definitely made it seem like they were a couple, albeit one that didn't work out in the end(I myself never saw it until years later after when I'd already played the game a bunch of times). I can also see how Cloud's reaction to Aerith's death could seem very romantic if they picked C/A options up to that point. Especially if they saw that "love that can never be" commercial before playing the game. I would agree that they were likely to end up together if Aerih'd lived. That is, I would've agreed if Tifa didn't exist. But that particular 'if' is a
huge one.
Anyway, Aerith is the first of VII's main heroines we see. Actually she's the first
character we ever see in the game, isn't she? VII opens with a scene of outer space then a close-up of Aerith's face. Shows her walking through the slums of Midgar before the "camera" finds it's way to Cloud and AVALANCHE on the first mission of the game.
It's been over a decade since the first time I ever played VII but I remember thinking something along the lines of "Oh, that's probably the main girl". I was definitely expecting to meet up with her very soon after. When Cloud bumped into Aerith after the first mission I chose the option to buy the flower from her. Well after that exchange I felt that, yeah, this was the main girl.
From this point on different player choices, speaking to NPCs at specific times.. depending at what the person playing does or doesn't do obviously changes your perspective.
I shifted mine from C/A to C/T pretty much at the beginning of the game.
The first time you
can see any kind of hints towards who Cloud likes is right after you return to Sector 7 from that first mission. When you try to follow the party into Seventh Heaven, well if you do it quickly enough, Barret will tease Cloud about seeing his "little baby". You have two options to respond to him with, but either one gives the impression that Cloud *might* like this girl a little. You can see the little interaction between :56 and 1:12 of this vid:
(^If you choose "Out of my way!", I believe Barret says something like "Heh heh... Jes calm down. Don't want nobody suspectin' nothin'.)
This is optional. If you take too long to approach Barret he skips to the "Ok! Go on ahead." part. (Also inside Seventh Heaven sometime at the beginning of the game, I'm pretty sure it's right after you give the flower to either Tifa or Marlene, if you talk to Jessie
before trying to exit the bar to get Barret to come tromping in, she's jealously grumbling about Cloud being all excited to be around Tifa. So that's another little bit of dialogue that steered me toward C/T early on. There's also
another bit around the same time where speaking to a NPC reveals that everyone in Sector 7's been gossiping about how well Cloud and Tifa have been gettin' along or something, not to mention Johnny acting jealous and kinda confrontational to Cloud because Johnny's like, obsessed with Tifa or something.)
I just
happened to see this stuff. I thought it was cute. I started choosing any C/T options I could. I just
happened to start shipping VII's canon couple on my first ever play through FFVII. The first play is pretty important, and it's why a lot of shippers continued to hold onto C/A even after its possibilities all fell through.
Well, my reply was more of a general thing than one directly to Nursie.
Just trying to say that first impressions are obviously important and it's why this went on for so long. And stuff. Also, sorry that I'm not very concise in my typing, but I just woke up/my cat died.
The only dialogue I remember with Cloud at the end is in the FMV, where he talks about meeting Aerith in the promised land. 
It could go either way. 
Yes, I told you I was a sick, twisted person. No proof, no evidence, just pure fanon. XD 
