Katy Perry says John Mayer is her biggest crush.

The 'Roar' hitmaker harboured secret feelings for her singer/songwriter boyfriend long before they got together and still can't believe she is dating her dream pin-up.

Quizzed if she has a cinematic crush, Katy quipped: ''I actually am dating my crush. I had a crush on him for a long time, and it just so happens we fit together great.''

The 28-year-old star likes snuggling up with John to watch romantic movies, but always ends up sobbing into his shoulder - which can prove embarrassing during long-haul flights.

Discussing her favourite films, she told W magazine: '' 'The Notebook'. And 'Titanic'. And I always cry on planes. My boyfriend [John] and I call them 'deprivation tubes' - you have a glass of wine, and you're watching a movie, and then, wahhhh.''

Katy also touched upon her 14-month marriage to comedian Russell Brand, which ended in December 2012, claiming it just wasn't meant to be.

Asked if she liked being married, she sighed: ''Of course. I really loved it. It was a new, fun, exciting journey. But I like how I am now, and I think all things happen for a reason.''

The pop princess made her first foray into acting by voicing Smurfette in animated flick 'The Smurfs 2' and would love to be offered more film roles, but she doesn't think she'd make it to set on time as she is incapable of getting up early in the mornings.

Katy joked: ''Yes [I want to act], but I hate mornings. So I told some executives who had asked me whether I wanted to act that if you want to start shooting at 11am, then I'm your girl. Otherwise, I'm not interested.

''I live a rock-star kind of life where I don't go to bed until 4am. I'm very nocturnal. But I always say that if Ridley Scott wants to hire me for 'Blade Runner 2' to play Rachael, I am absolutely available.''