When Uma Thurman hit the red carpet without sweetie André Balazs, 49, at this year's Oscars, for many it was the first sign that something was amiss in the two-year romance. In fact, trouble "had been brewing for three months," says a source. "But Uma knew that if she was going to make a break and start life anew, she [couldn't] parade him up and down the red carpet." Three days later on March 8, the actress, 35, confirmed the split. "It's true," she said. "But we remain close friends."

So what caused the demise of the picturesque pairing? Reps for both declined to comment, but the source says Balazs "was talking about marriage, and [Thurman] was just having fun. She was not ready to recommit to a lifelong partnership. And she realized that it would either go one way or the other." The two started dating in 2003 after Thurman separated from Ethan Hawke. (Balazs, like Thurman a parent of two children, had just endured his own split from Ford Models CEO Katie Ford.)"They both answered things they wanted out of life at that time," says R. Couri Hay, a friend of Balazs's. "But they just didn't take the next step."