Doofenshmirtz wants a girlfriend, so decides to create the Love -U- Later Inator. Deciding to just fire it, he does. Unfortunately, it doesn't work for him and starts firing willy nilly, and it hits Phineas, Isabella, and Candace and Jeremy! So suddenly, Phineas loves Isabella more than ever, and Isabella is overjoyed. Fortunately Ferb wasn't hit, and gets worried about Phineas as he is going out to see Isabella more and more. Ferb is also upset that nobody loves him. Will Ferb (with Vanessa's help) find out the source of Phineas's sudden affection for Isabella?