I believe it was to give Mia a "love life", probably because the makers decided it was a chick-flick and they might as well make the next one more "girly" so it would be better defined
Princess Diaries second edition or 'Take Two' is about a Royal Date of Helen Thermopolis (Mia's mom) and Mia's algebra teacher (Mr.Gianni).And Mia wants to find her secret admirer(A person keeps on...
Several actors that appear in both Princess Diaries 1 and 2 are:
Julie Andrews, played as Queen Clarisse Renaldi.
Anne Hathaway, played as Princess Amelia.
Héctor Elizondo, played as Joe.