There are no characters named Paolo or Isabella in either "Lizzie McGuire" the show or the movie.
Here are some popular characters from "Lizzie McGuire":
* Lizzie McGuire: The main character, played by Hilary Duff.
* Gordo: Lizzie's best friend, played by Adam Lamberg.
* Miranda: Lizzie's best friend, played by Lalaine.
* Ethan Craft: Lizzie's crush, played by Jake Thomas.
In "The Lizzie McGuire Movie," the main romantic interest is Paolo, played by Yori Boyajian. While the movie features other characters, there is no Isabella.
It's possible you are remembering a different movie or show altogether. If you can give me more details about the characters, I might be able to help you figure out what you're thinking of!