There's absolutely no indication Zack and Aerith ended up together and later material disproves it. Not every game needs a complete happy ending and I prefer VII's to be bittersweet, even if I don't really like CloudxAerith.
Now, can that be your interpretation? Sure, but it's also up to the player to decide if Cloud chose Aerith.
As for VIII, I think there's a big difference when saying "whatever" and "I'm sorry" even if I think people exaggerate how much he uses whatever. Have you played the Japanese version?
Didn't FF7 AC show Aerith with Zack? Even though they're gone they're chilling together through the movie.
Yes I originally played the JP version on PSX about 3 times, got all the rare mags and ultimanias related to FF8, and most recently the vol2 with all the previously unreleased FF8 sketches. From what I know of the localisation team, they weren't going at it hamfistedly and more often than not, those 'changes' to translation that fans later discover are ones the team was specifically told to do by the same JP staff that made the game and characters. The JP staff knows english too, the diff is that localisation is more than translating word for word, it's about keeping a similar tone and feeling.
I made these page ages ago, but as you can guess I've only ever focused on changes to Rinoa
http://rinoa.nu/rinoa/dialogue5.php
http://rinoa.nu/rinoa/changes.php