since Phineas has Isabella, Ferb should have a girlfriend too (and pairing him with Vanessa Doofenshmirtz wouldn't work in the long term since she's about seven years older, and she already has a boyfriend)
Happy Birthday, Phineas! Even though its not your birthday yet! But still Happy Birthday! Remember this is just a PROMO. NOT the episode. Phineas and Ferb is owned 의해 Dan Povenmire and Jeff "Swampy" Marsh.