But why does SE point out Cloud and Aerith's special bond in comparison to Cloud's other love rival, Tifa?
Because for most people, there's not a need to PROVE by scaping for every piece of "evidence" that Cloud loves Aeris, not Tifa.
People like your goodself aside, and people with short attention span, FF7 is a very simple story once you play it twice. First time, it can confuse, second time, it's evident. Japanese literature doesn't spoonfed its audience like the West does. It doesn't feel an obligation to explain what is obvious. By saying Cloud has a special bond with Aeris it's highlighting a key aspect of Cloud's arc. His bond with Aeris - his code, his honour, his respect and his responsibility - and his acceptance of how important she was, are all absolutely key to Cloud's personality. This isn't love. This is character arc. His guilt is built on all these factors, just as his failure of Tifa, his hometown, Zack caused him to breakdown. His bond with Aeris is special - its key to Cloud as a character. It's not love. You want it to be love, that's the key issue here and you will hunt anything which will justify something that any sensible man will look stunned at.
If you need to find quotes from books to prove to you are righteous on a commercial, mainstream, made for family entertainment video game, either the game is crap and can't tell a story, or you're looking for story that isn't there.
The rationale for love is this: Cloud found Aerith physically attractive. Cloud agreed to go on a date with Aerith. Cloud thought Aerith was funny. Cloud was triggered into a romantic flashback after meeting Aerith. Cloud told Marlene he hoped Aerith liked him. Cloud flirted with Aerith in-front of Tifa. Cloud was willing to risk his life to save Aerith, a girl he had just met. Cloud went on a romantic date with Aerith in Golden Saucer.
Cloud and Aerith did things that Cloud did not do with any other character. These things that Cloud and Aerith did together tell us that Cloud's "special bond" with Aerith is not the same as Aerith's "special bond" with the other characters because Cloud and Aerith shared a bond that was more than just platonic, it was romantic.
You played Cloud's romantic date? It's not romantic. Have you watched any Japanese films or read the books? Cloud is a typical teen archetype - dragged into romantic subplots against his certainties. That's the comedy, not romance.
And again, the one irrefutable fact you sidestep because it destroys the whole debate - Cloud was sick. He wasn't himself - literally. He was in the middle of a mental breakdown. Aeris was falling for a guy who reminded her of her lover. Is that all really romantic? Is it love I hear in the trees singing this tale? It's not. Cloud cares for Aeris. She's attractive, she is charming and he is her guardian in his mixed up world. Could they have enjoyed some seeding under a Highwind in a world where he wasn't mad and she wasn't mourning? Quite possibly. Aeris is meant to be so charming ALL the heroes love her. So no doubt.
But not in this tale.
Not true: "I, now undoubtedly, love Cloud much more than Zack.” ~Aerith’s monologue in Gongaga, Final Fantasy VII Dismantled, Square Enix
Go re-read Maiden. It gives you lots of nuances to Aeris' confusion between her romantic love for Zack, her infatuation for Cloud, her anger at Zack and inability to see how much Zack means to her. This works in tandem with FF7 - she doesn't know Zack's demise, she feels abandoned, and here's this Sub-Zack - or maybe Better-Than-Zack that is alive and well (or so she thinks).
Aeris' love is Zack. Read Maiden, that once holy bible of shipping, read it properly - change the names of Aeris, Cloud, Tifa and Zack and read it without any loaded aspirations or hopes. It's actually a very clear document to who Aeris is. It also makes clear what you don't see in FF7 because the character is unaware of key facts regarding Zack and Cloud.
Barret observes that it is Aerith, and only Aerith, that is able to bring out the real!Cloud while he was profoundly messed up in multiple ways. That's pretty impressive that Aerith could do that.
But she doesn't. Only person who brings out Cloud, is Tifa. Not Aeris. Either way, whoever did, doesn't prove romantic love.
Mothers and families can be vital in helping a child. Doesn't mean incest.
Once again, if you truly want truth, step back. Forget the Western expectation for every aspect of a story to be dotted and crossed and spoonfed. The CloudxTifa thing is evident, but its not pivotal to FF7's story, because well, romance isn't actually that interesting. It's what I love about Japanese storytelling (or at least, some of it, not wanting to generalise), but they don't spoonfeed as we do. Cloud went to Soldier to impress Tifa, he fails, in fact almost comically fails, by failing to save her, their hometown, their families and even his hero. That's mega bad fail. Breakdown fail. He then plays the persona of the Hero he aspired to, unwittingly to his hero's girlfriend! Oh the hilarity! He then fails to save her too! Breakdown time again! In the end, the only one who can break through the mad is the girl he went to impress in the first place. They go off, become a couple, but happiness can't last with that tragedy bag on his back, and his relationship, his friends and his responsibilities fall to the wayside as the guilt and disease take him. He feels so hopeless and useless he can't face anyone, and fears helping anyone (now go look back at the comic tragedy and you can see why, seriously, Frank Spencer has had less catastrophic moments). They all forgive him. They all tell him to move on. He does. And to give everything a happy ending, he sees Zack and Aeris united in death as he's united in life.
Now that story is big, mad and complex. Having to point ot who Cloud loves in that story shouldn't really be a vital point, should it? If he doesn't love Tifa, half the story makes no sense, if Aeris loves Cloud more than Zack, Advent Children loses its happy ending - and in both instances the Way to the Smile novellas are, well you have to say they didn't happen, just to make it so Aeries loves Cloud, and doesn't really like Zack and Cloud loves Aeries, and just puts up with that girl he once wanted to impress. It's mad. Madness! Madness!
You could do a comedy to Cloud's horrific bad luck. It's mind-boggling when you write it out.