Sora couldn't much say if he normally got that invested in movies, considering he didn't grow up seeing that many, so it was most likely because he had lived it. It was pretty easy to cheer for people that he had met in reality, even if the movie wasn't quite reality for him.

With that, it was just a matter of the movie wrapping up, since Ariel was choosing to stay on land and live with Eric. "Wow, she didn't stay that long in the ocean...when I was there, Eric offered to swim with her, too."