The couple, who began dating two years ago, apparently want different things in life.
“Stacy called it quits. She wants to have children and a family someday. She knows where George stands on that,” a source close to the couple tells PEOPLE exclusively. “They talked and they quietly stopped being a couple several weeks ago.”
The source also says Clooney, 52, and Keibler, 33, will remain on good terms: “They talk every day. They were friends before they started dating and they’ll be friends after. It was a friendly [breakup].”
Although she wants to be a mom one day, it’s clear Keibler is already a dedicated godmother. She Tweeted a birthday wish to her goddaughter with a series of hashtags – “#mylove #myheart #mygoddaughter” – on June 10, before posting an inspiring message the next day about going through tough times. “Trying times are not the times to stop trying,” she Tweeted.
The news of a split comes after the pair have spent a lot of time apart. They were last photographed together in March in Berlin, where Clooney was filming his upcoming drama Monuments Men.
In a recent interview with PEOPLE to promote her new show Supermarket Superstar, premiering July 22 on Lifetime, Keibler spoke about her hectic schedule and her desire to travel this summer.
“My schedule is keeping me pretty busy until the show airs and then hopefully I’ll get the chance to go to Europe,” she said. (Look for more from Keibler’s interview in an upcoming issue of PEOPLE.)
But while Clooney was photographed boarding a boat near his Italian villa on July 4, Keibler partied with girlfriends in Los Angeles at a starry bash thrown by top Hollywood manager Guy Oseary and hosted by DeLeon Tequila.
“They haven’t seen each other in a while and they’ve both been working so much, so in recent months, they’ve started growing apart,” a second source tells PEOPLE.
• With reporting by AILI NAHAS