As you may or may not know, a new 1-hour special came on about a week ago. Isabella and Phineas hugged each other not once, but twice in the special. First let us cover "Phinbella episodes": The Beak and Phineas and Ferb Summer Belongs to You!. And, again, you may or may not know, a new TV movie, Phineas and Ferb The Movie: Across the 2nd Dimension, is coming out next summer (September for Germany). The movie's plot is about when Phineas and Ferb find out that Perry is a secret agent and must join with Perry to defeat a more powerful Doofenshmirtz.
Here's my theory: Phineas and Isabella are gonna kiss. I have no idea how it's gonna happen since Phineas has a triangular head.
If you agree with me or disagree with me, comment. If you have a different theory, comment. If you have a theory of how its gonna happen, comment. Whatever you do, just comment.