User blog comment:Phineas7897/ferbs girlfriend/@comment-1463891-20091203044300

Simmer down about the "Aunt Isabella" reference in Quantum Boogaloo; once you're dealing with future timelines, all bets are off. And MasterHearts, I don't believe we ever found a source for that "Dan" quote.

As for Ferb and Isabella, I just can't see them getting together because I don't think Ferb would do that to his brother. I think there's something there between Phineas and Isabella, and Ferb (being closer to both of them then anyone else) knows it.