Why does it make Tifa a heart broken side character and Zack a loser though? I don't really get the Tifa can't exist without being a love interest thing because she went a whole six years without Cloud, she made new friends, became part of a family of friends.
The writers sticking the one thing I get, but I also have faith in writers being able to write something different without leaving characters in a bad place.
I don't want to dogpile on you, I just think it's a damn good question so I want to add my perspective since I haven't
seen it.
Because what I want to talk about is the author's intent - and Nojima has plenty, as Nomura himself stated recently.
The thing is, if CA was meant to be, I think there would be no need for a Tifa. When they decided to kill Aerith, they created Tifa so she'd stay by the hero's side until the end - that was told in an older interview; however, this being a Final Fantasy game, if the devs had wanted to portray a love beyond death with CA, they wouldn't need a Tifa. They could come up with every excuse out there so that Aerith would fill both the roles of the internal and external plot, this wouldn't be a first. They'd have made something very bittersweet, with them reuniting in the Lifestream after her death, at the end, him sensing her etc.
But they chose not to. Because that was not the story they wanted to tell. What they wanted to tell was a story of death, how you'd feel when that character died, and how to accept death, so you can live.
So they created Tifa and woven her story with Cloud's, so much that many thought she didn't even have a story. But she did, for the most part she had the same memories, the same past, the same trauma. And thus was born a character with the role of helping Cloud, and discovering his love for her in the Lifestream scene. This is why I say that the story does not work if Cloud falls in love with Aerith; because it's not her
role. In the OG we can clearly see that Aerith chose the Planet over Cloud when the time to chose had come; when Tifa had to make the same decision, she chose Cloud. And it makes sense because these are the decisions that, as heroines of the external and internal plot, they're always going to make. Aerith cannot have what Tifa has, and Tifa cannot have what Aerith has.
And Tifa not only has the key to repair Cloud's psyche, but she also has his love, and loves him as deeply in return. REMAKE told us they were thirsty for each other, but REBIRTH tells us what kind of couple they're about to become - domestic talks, intimate talks, supporting each other when their PTSD hits, being very aware of each other's need. This is what Aerith is envious of, because she wants it. The church scene boldly asks "but does she want it with Cloud?" in a very meta way. The lovers beyond death theme may exist, but not with CA. That is Zerith coded, and the game took its sweet time to tell us about it, to give us the biggest cue towards the end.
Once again, Aerith chose to pray for the Planet. And I'm betting that once again in part 3 we'll see Tifa chosing Cloud and staying in Mideel with him. This is the authors' intent, to show Aerith's death as a loss, someone who loved life and was unfairly murdered, cut off from this life she loved. And Cloud and Tifa fill the theme of life, they're both survivors, both in love with each other - another "life" theme, starting a life together after the game. Because life is also about accepting death - a theme AC/C does come back on so that Cloud can finally put that guilt away.