[Tifa.]
Well... Tifa was crazy for Cloud before Aerith even came into the picture, in my own opinion. And Aerith is not with the living, so there is no possible way. surprised
Honestly... when I first played the game; I used to hate Tifa. Why?
Well, even Tifa admits that she never noticed Cloud when they were kids. No matter what he did, she never noticed. Even after the bridge collapsed when they were kids, where all the other kids abandoned her, and Cloud tried to save her.... she never noticed him (Side note: I do acknowledge now that this is because she did not remember what exactly happened.)
Cloud states that because after this since Tifa continued to ignore him he believed that Tifa blamed him for the accident as her father did. Angered by his own weakness to prevent the accident, Cloud gets into fights all over town. Meaning hince... Tifa was indirectly the cause of his childhood problems.
Tifa only began to notice Cloud at the well in my opinion because now nobody else was...
Tifa: All the boys are leaving...
Tifa was a very popular person.... but suddenly everyone leaves. Yet... there's one person that still wants to see her. Amazing how she finally notices him after everyone else leaves, ne?
Tifa, in my opinion, practically pushes this promise onto him. Which is the only reason I believe she checked the newspapers for him. ....Because Cloud would have to be a famous hero like Sephiroth.
Fast-foward now.... pre-game present time. Now... as far as Tifa knows everything she once knew is now dead and gone forever. Yet.... out of no where she stumbles across Cloud... and need mind you... does not recognise him.
I honestly think Tifa's feelings for Cloud spurred from a need to cling to what past she could. I do honestly believe if someone else had survived (anybody... it wouldn't have had to have been someone to start a romantic relationship with) she wouldn't have had such deep of feelings for him as she does in the game now. She would have still cared for him... but since there was something else for her to cling to the feelings wouldn't have gotten so deep.
In the long short of it... I think that Tifa only likes Cloud because she believes he's all she has left.
Now... after a few more times of playing the game Tifa became my third favorite character... but these opinions on the Cloud/Tifa relationship still stand. The base of their relationship would be that of settlement (not exploring all opportunities or taking chances to find what they really need and want) which is unhealthy and they really could not support each other where needed (see my rant on the Zack/Tifa pairing in the "Who's your favorite coupling?' thread)
In the end.... Unless one of them made some big changes and grew an emotional spine (sorry but neither do have one... sorry) the Cloud/Tifa relationship would be doomed to a lot of hardships and heart break.