The 40-year-old actress, who also directed the film said they both could feel how they reacted after a serious fight, reported Aceshowbiz.
"Brad has never seen what I'm like when he's left me after one of our fights. Sometimes I'm strong. But as soon as he leaves the room, I melt into tears.
"With this film, he sees it. And I see into his private moments.I filmed it and I discovered his expressions. So I better understand his frustrations over certain aspects in me," Jolie said.
"The most difficult scenes were the most drawn-out fights: normally if Brad sees me cry, it ends by his taking care of me. But here, in the film he had to stay angry, and I couldn't take it personally.It was so strange and interesting," she said.