This is Airborn by Kenneth Opal.
Airborn is a 2004 young adult novel by Kenneth Oppel. The book won the Canada's Governor General's Award. Airborn is set in a time where the primary form of air transportation is the airship. The technological advancements in the story appear to depict a world similar to the very early twentieth century, with a few changes: the airplane has not been invented and the Earth contains hydrium, a fictional gas lighter than hydrogen, as well as fictional flying creatures which live their entire lives in the sky. This suggests that the book takes place in an alternate reality. The book takes place aboard a transoceanic airship, the Aurora, and is told from the perspective of its cabin boy, Matt Cruse.
the protagonist works on a passenger luxury airship.
Matt is a cabin boy on the ship
he is trying to get a girl named Kate,
I can't find specific reference to her as a love interest, but Kate is the primary female character in the book.
but she seems to curious in proving the existence of a species of flying cats that her grandfather wrote about.
She has her grandfather's journal with drawings of what they call "cloud cats"
then the ship crashes, and pirates try and take over.
Pirates attack the ship, causing the ship to crash.
I remember that the author was Canadian (he lives in Toronto).
The author is from British Columbia.
i also remember that instead of using hydrogen or helium, the airships use hydrium,
The ship uses hydrium.
which the island they crash on is full of.
The island they crash on has hydrium and cloud cats on it. (How convenient!)
i think this was a series. im not sure.
Airborn was followed by two sequels: Skybreaker and Starclimber