Selphie and Riku?
I highly doubt that Riku and a Fianl Fantsay character will get together. Besides, I think Riku would become accedingly annoyed by Selphie is they were a couple.
And as for Cloud and Aerith, its obivious that Aerith has strong feelings for Cloud (although they aren't neccessarily romantic). She wants him to be careful and wants to be part of his life, but before he dissappeared, he really pushed her away. =/ Besides, I don't think it would ever work out. Aerith is a quiet, but sweet, caring, and very delicate young women. Cloud is a strong, silent, very pessimistic young man on a quest to fight his darkness. They don't compliment each other well. Tifa, on the other hand, is a determined strong women who isn't going to let Cloud push her away! The way Aerith is, if they became a couple, Aerith would need Cloud emotionally and basically be much more needy. She wouldn't want him to be in any danger. Tifa, on the other hand, is strong and can take care of herself. If Cloud needs to fight Sephiroth, she's not going to try to stop him, but be right there beside him. Therefore, Cloud and Tifa compliment each other much better in the Kingdom Hearts world, although I doubt there will ever be too much romance between them, just considering that romance is not a theme of KH.
And Sora and Riku are STRONG FRIENDS. They feel no romantic feelings for each other, but they do love each other, just in a different way. They've been inseperable since they were young children. They have a very strong bond. After the door to Kingdom Hearts closed, Sora didn't know if he'd ever see Riku again. And to be reunited with your best friend ever, when for all you knew he could be dead, has got to be emotional.
And its basically the same with Roxas and Axel. All they have are each other. They face a grim existence, and they are not only each other's best friend, but their only friend. Therefore, their bond is just as strong as Sora and Riku.
