"It's not a big movie, not an action movie," she reveals. "It's the kind of movie we love, but aren't often cast in."
"It's a very experimental, independent type film," she continues. "Where we get to be actors together be really raw, open, try things."
Jolie and Pitt's romance began on the set of Mr. & Mrs. Smith, and the two have been together ever since. The couple got engaged in April 2012, and the actress says her future husband is "family."
"He's not just my lover and partner," she asserts. "Which he is, wonderfully, but he's my family now."
"We have history and work hard to make it great," she adds. "We don't kind of relax about it and take each other for granted. So, like everybody, we have our challenges, but we're fighting to make it great."
Jolie will next appear as the title character in Maleficent on May 30. Pitt's next film is Fury, out November 14.