Ferb and Vanessa's relationship

Ferb and Vanessa seem to have a good relationship. It is probaly on the same terms as Phineas's relationship with Isabella, because they aren't offically dating yet.

Ferb's Opinion of Vannesa
Ferb has first seen Vanessa in I Scream, You Scream. Though at the beginning of the episode, they just see each other, at the end of the episode it is revealed that Ferb has a crush on her. Thier relationship is briefly seen in The Chronicles of Meap, when Ferb is seen in a rocket next to Vanessa, and she seemed impresessed. Ferb still has a crush on her, and is nice to her, helps her, and gives her advice.

While recovering the Pizzazium Infinionite
Thier relationship is also later explored in the episode Vanessassary Roughness. While at the Superduper Mega Superstore, Vannesa is trying to find pizzazium infinionite to impress her father, but Ferb decides to help her once Candace, Stacy, Baljeet, Buford, and Perry start stealing it. Ferb and Vanessa worked togethor, and eventually found it. Ferb even saved Vanessa from being chopped to death by a lawn mower. In that episode they seemed to get more effection for each other. Vanessa kissed Ferb on the cheek later, and he went into another fantasy. This episode revealed also that Ferb would risk his life for Vanessa.

While at Paris, France
Later in Season 2, while Phineas and Ferb are traveling the world, Ferb stumbles upon Vannesa in Tokyo Japan. They instantly reconized her, and invited her to go to Paris, France to refuel. While at Paris, they rode togethor on a motorbike, and had a good time. At the top of the Eifel Tower, Ferb gave Vannessa some advice about how to relate to her father. While there, he noticed a florest, and bought flowers for her. Though when he went back to give the flowers to him, she was off with Doofenshmirtz. Ferb was then sad. (Phineas and Ferb: Summer Belongs To You)

Vannesa's Opinion for Ferb
When Vannesa and Ferb first met, she just thought of Ferb as another boy on the street. (I Scream, You Scream) She then started get more feelings for him, and they even kissed.

While recovering the Pizzazium Infinionite
Though, in Vanessassary Roughness, she actually got to know Ferb. Ferb even saved her life after being nearly being shredded by a lawn mower. She thanked Ferb for helping him, and kissed him on the cheek.

While at Paris, France
In Phineas and Ferb: Summer Belongs To You!, Ferb save Vannesa's life again, but didn't expect to. Vannesa went on the plane with Ferb, to travel around the world. Once they got to Paris, She let Ferb ride on her motorbike with him. When on the top of the Eifel Tower, Ferb gave Vannessa some advice on her relationship with her dad, and she saw her dad a on Perry's hovercar, she went with him, and took Ferb's advise. She thanked Ferb, but Ferb thought she went with a differnet girl.

Romantic Moments
In Vannesasary Roughness, Vannesa kissed Ferb, except only on the cheek. In Phineas and Ferb: Summer Belongs to You, they rode a motorbike togethor, and were togethor on the top of the Eifel Tower.