Joaquin Phoenix thought Rooney Mara ''despised'' him when they first met.

The 44-year-old actor met his now-fiancee when they worked on 2013 movie her and he initially mistook her shyness for a very different feeling.

In a new interview with Vanity Fair magazine, the US publication noted: ''He believed Mara despised him during the making of 'Her' but later learned she was just shy and actually liked him too.''

And the 'Joker' star - who also worked with Rooney on 'Mary Magdalene' - admitted the 'Girl With the Dragon Tattoo' actress is the only woman he's ever researched online.

He told the outlet: ''She's the only girl I ever looked up on the internet.

''We were just friends, email friends. I'd never done that. Never looked up a girl online.''

The 'Walk the Line' actor admitted he feels ''so fortunate'' that he's had so many great opportunities and experiences throughout his long career.

He said: ''Rooney said to me the other night, 'Do you realise how many great opportunities you've had? These films?'

''I said it's true, I've been so fortunate, so many movies where I was like, I don't know if I'll ever be able to top this experience. The experience of making this movie. It was incredible that I found another one.''

And even if he doesn't have the best experience, Joaquin has learned to just focus on the other areas of his life that are so positive.

He added: '' I think only recently, as you get older or whatever, you're okay. You go, 'Maybe it is going to be a bad experience' or 'Maybe I'm not going to enjoy it. And maybe I won't have any of those connections, maybe I'll feel just hollow afterwards.'

''That's okay. Because I know that I have meaning in other parts of my life. And that's really what sustains me. I enjoy it. I love my life. I f***ing love my life.''