Um... I feel like you played a different version of KH1 then me. Yes, she had a moment where she questioned, if it could ever be the same between them, noting how he's lost his heart/self, but she was also quick to say "Let's go" implying she wanted to join Sora on the last bit of the journey to get Riku back. Whenever you talk to her afterwards she notes that Riku is strong in a text dialog, I read it as her encouraging Sora not to lose faith in saving Riku.
When she was sent back to the Island, Sora had already made it clear he though her tagging a long would be too dangerous and that she'd just get in the way.