Phineas and Ferb are teenagers.
One day they went to school, and Isabella was dreaming if Phineas would say, "I love you", to her.
Whatcha doin', Phineas? "Oh, just lookin' for Baljeet," said Phineas. "He's over there Phineas." "OK, thanks Isabella," said Phineas. "Bye Phineas," Isabella would say.
There's a new girl in Colcreek Highschool, her name is Cathy. Cathy has a huge crush on Phineas, and Isabella was so jealous that she wants to punch her. When class started, Isabella stared at Phineas, and looked over; Phineas was sitting next to Cathy. Isabella crumbed her test paper and her teacher sent her to Mr. Kea's office (the principal).
Isabella felt totally embarrassed by her teacher, Mrs. Pod. She started crying, and was afraid Phineas liked Cathy, and not her. After she had explained to Mr. Kea what happened, she had to spend her time in the principal's office.
When school was over and Mr. Kea was talking to her, she looked out the door and saw the Fireside Girls: Adyson, Gretchen, Katie, and Jenny, gathered around Phineas. She started crying, and the Fireside Girls just looked at her in Mr. Kea's office, and giggled. Isabella looked away, and said, "focus on my education."
After school, Phineas said to Isabella that he doesn't like Cathy. Cathy heard that and started to cry. Isabella hugged Phineas.