Paul Dano has revealed he and actress girlfriend Zoe Kazan tried not to get "too cute" on the set of their new film Ruby Sparks.
The real-life couple play young lovers in the first flushes of a relationship in the indie film, which Zoe also scripted.
There Will Be Blood star Paul said: "Hopefully we weren't getting too cute when the cameras weren't rolling. I tried to stay away from that."
He added: "On this film we were so busy, we're in most of the scenes. I feel like we were there more for Calvin and Ruby than we were for each other almost during the day at work, which I think is good, we just cared about the film.
"Going home after a long day there were challenges occasionally but I think our dynamic was ok."
Next up for Paul is the nineteenth-century drama Twelve Years A Slave, which also stars Brad Pitt and Michael Fassbender.
"We did it this summer in Louisiana. It was hot and an intense subject matter, but I got to work with some wonderful people and I loved (director) Steve McQueen very much. Hopefully it will be a good film," he said.
:: Ruby Sparks is released on Friday, October 12