People.com Celebrity Demi Moore and Ashton Kutcher's Marriage: How It Turned Toxic "She drove him crazy after a while with questions and doubts," his pal tells PEOPLE By Michelle Tauber Michelle Tauber Twitter Michelle Tauber is the Senior Editor overseeing Royals coverage at PEOPLE. She has been covering the royal family for PEOPLE since 2000, including William and Kate's wedding, Meghan and Harry's wedding and the births of the royal children. Formerly PEOPLE's first and only Head Writer, she has written a record-breaking 250+ cover stories spanning celebrity, crime and human interest. A graduate of the University of Florida, she lives in Orlando. People Editorial Guidelines Published on November 21, 2011 01:00 PM Share Tweet Pin Email It was an unlikely romance from the start – and in the end, the six-year marriage of Ashton Kutcher and Demi Moore fell apart because of issues that had long fueled skepticism about their relationship: their famous 15-year age difference, his wandering eye, her insecurities. As a result, the marriage “[had] been deteriorating for a long time,” a friend of Kutcher, 33, tells PEOPLE in this week’s cover story. “Ashton was ready to end it, [but] he wanted to wait for Demi to actually do it. He loved her but couldn’t live with her. ” Moore, 49, “really wanted to save the marriage but couldn’t deal with the pain of his cheating,” adds the friend. “They were fed up with each other,” a second source tells PEOPLE. PHOTOS: Ashton & Demi: Portrait of a Marriage Several friends note that the age gap between the former power couple – who are worth an estimated $290 million – caused Moore to doubt herself. “If anyone was uncomfortable with the age difference, it was Demi, not Ashton,” says a Kutcher pal. “She drove him crazy after a while with questions and doubts.” For much more on Demi and Ashton’s tattered marriage, pick up this week’s issue of PEOPLE, on newsstands now