The actress has revealed that the couple do not restrict each other and says she doubts fidelity is essential.
Speaking to German magazine Das Neue, the 34 year-old said: 'I doubt that fidelity is absolutely essential for a relationship. It's worse to leave your partner and talk badly about him afterwards.
Neither Brad nor I have ever claimed that living together means to be chained together. We make sure that we never restrict each other.'
However, she added that the couple have a fiery relationship at times.
She said: 'The sparks fly at home if the nice Brad fails to see that he's wrong and reacts in a defiant way. Then I can get so angry that I tear his shirt.'
The revelation will shock fans of the couple, who have have a family of six children, three of whom are adopted.
Brad and Angelina first got together in 2005, allegedly while filming on the set of Mr And Mrs Smith, when Pitt was married to Jennifer Aniston.
And although seemingly condoning infidelity in the interview with Das Neue, Angelina has denied Brad Pitt cheated on Jennifer Aniston with her.
She said: 'To be intimate with a married man, when my own father cheated on my mother, is not something I could forgive. I could not look at myself in the morning, if I did that.'
A new book, Brangelina: The Untold Story of Brad Pitt and Angelina Jolie, by author Ian Halperin, makes a number of claims about their relationship - including accusations that Angelina Jolie of maintains a jungle hideaway in Cambodia where she used to meet former lover Jenny Shimizu for trysts.
Halperin also alledges that Brad Pitt had several liasons with an obscure Sudanese model, whom he allegedly met in 2007.
The Canadian undercover reporter, claims to have gained access to several insiders close to the couple, and it's these sources who have provided the material used to write his book.
He said: 'When I was undercover as a paparazzi at the Chateau Miraval in 2006 when she was giving birth to the twins, I was able to befriend several people working for them.
'Everyone was at the hospital at Nice while Angie was in there, but I stayed behind.
'I knew that was my golden opportunity to befriend several people close to them. That's when I made my really key sources.'