In that singular quote it's not clear, but in all the other quotes, it either says they are or uses phrases with the same idiomatic tone as 'feelings for each other' has in english.
a'ight.

Now who's reading too much into things? He doesn't say he wants to do it alone. He just says he has to keep trying.
Sure, when you look at it alone, it seems to be that way. But when you compare the high and low versions....

Cloud (high): "Someday we'll find the answer. Right, Tifa?"
Cloud (low): "I'll find the answer some day, as long as I keep trying."

...the contrast between the two indicates that that Cloud isn't concerned with finding the answers together with Tifa.

And either way, he wants Tifa to be with him 'from then on' 'in a different way than before' in the start of CoT.
And this is where arguing for ambiguity in 2010 gets.... sketchy... and I'll admit it. The best counters to this, I suppose, are 1) that "different" could be referring to the idea of starting a 'family' with Tifa and others... 2) that not much later in the story, Tifa is still unsure if Cloud has feelings for her, and she can't bring herself to directly ask him if he loves her....and 3) that Nomura says he has 'no clue' if Tifa and Cloud share romantic interests between FFVII and AC, and that these matters have been been left up for fan interpretation.

Cloud is oblivious to any feelings Aerith has. ALSO from the U10. So no, there was no romantic bond. You have to be aware of the other peson's feelings to have a romantic bond.
You're right about the "Cloud is none the wiser to them" statement (which, for the record, applies to Tifa as well as Aerith) ... But the statement about Aerith's bond with Cloud is said in an objective sense; it's not about what Tifa feels is going on between them. So a bond exists between Cloud and Aerith, at the very least while she is still living. It is special, different from Tifa's, and causes "complex feelings" within Tifa as a love rival. What kind of bond could it be, then, if it's not knowingly romantic? The best thing I can think of is that it's a subconscious bond of romantic potential, which Tifa can sense by the way Aerith and Cloud naturally act around each other.

Come to think of it, it seems like the 'none the wiser' can only refer to a state pretty early in the game... i don't know.

Then in AC her old jealous feelings are reawakened when she finds that Cloud is living at the church, for she gets the impression that he's drawn there for more reasons than just his guilt ("dragging the past around").
Uh, 'his guilt' IS dragging the past around. 'I failed people, I'll fail more people, I suck' is the basic idea of Cloud in AC/C. His guilt is what he's dragging, what she comments on him dragging around, and that's what he drags so much he wears it down, like he comments on later in the film.
Sorry I guess my statement was worded a little funny, but I actually was saying that "dragging the past around" refers to his guilt, BUT remember what all of the quote says, particularly the last phrase:

"The thing which she is unable to hide in her irritation towards Cloud is the fact that he isn't merely dragging the past around, but because that reason might perhaps be related to Aerith."

So Tifa intuits that the reason Cloud goes to the church isn't merely because of his guilt, because of something else related to Aerith. Put the sentence in context with the section being about the love rivalry, and there you go.