DEMI Moore and Ashton Kutcher called time on their marriage after therapy sessions developed into "intense rows".
The couple - who announced their intention to divorce earlier this week after six years together amid stories of 33-year-old Ashton's alleged infidelities - desperately tried to work out their differences but gave up when the fighting became too much for them.
A source told People: "Ashton is unhappy; [Demi]'s unhappy. It just got to a point where they had to end it.
"The fighting could get pretty intense. Whatever therapy they did was fine for a quick fix but could not get to the heart of the problem."
Neither party have directly commented on the cheating claims with Demi only saying in an official statement: "It is with great sadness and a heavy heart that I have decided to end my six-year marriage to Ashton. As a woman, a mother and a wife there are certain values and vows that I hold sacred, and it is in this spirit that I have chosen to move forward with my life. This is a trying time for me and my family, and so I would ask for the same compassion and privacy that you would give to anyone going through a similar situation."
Ashton added that he will forever cherish" his marriage to Demi.
He tweeted: "I will forever cherish the time I spend with Demi. Marriage is one of the most difficult things in the world and unfortunately sometimes they fail. Love and light, AK."