Pitt-Jolie have reportedly struggled during the last 12 months of their five-year relationship and the actor's brother Doug, 41, visited him in New York over Christmas urging him to pull the plug on the relationship because it was making his family unhappy, the Sun reported online.
"It's no secret they have been in a pretty loveless relationship for about a year. They barely spend time together and when they do it is very fraught. They want different things from life," a source said.
"Brad's family are being more vocal with their doubts over the relationship. The only thing they still have in common is their kids. That's keeping them together at the moment," the source added.
Pitt and Jolie fell for each other while shooting 'Mr and Mrs Smith' in 2004 where they played a warring couple on screen while the actor was still married to Jennifer Aniston, whom he divorced in 2005 to be with the 'Changeling' star.
Pitt, 45 recently spent the weekend taking part in George Clooney's Haiti telethon, while 34-year-old Angelina was doing a photoshoot for 'Vanity Fair' magazine.
Earlier, it was reported that the couple has signed a 205 million pound split deal after meeting a top divorce lawyer.
Jolie was also said to have become close with a Russian dialect teacher while filming her latest movie 'Salt' while Pitt's mother Jane continues to be in touch with ex-wife Aniston.
Pitt and Jolie, who have not tied the knot yet, have three adopted children-- Maddox,eight, Pax, six, and Zahara, five and three biological kids, Shiloh, three, and 17- month-old twins Knox and Vivienne.
The couple has not been photographed together in public in recent days. Pitt was last snapped at the Hope for Haiti concert on Friday without Jolie. His ex-wife Aniston was also there with her rumoured boyfriend Gerard Butler.
However, a report by US tabloid has denied that the couple are on the verge of a split, with a source close to the couple calling the reports "totally false".
"Everything is fine. It's business as usual," a source told People online.