Since news of their split last week, new details are emerging about what went wrong for George Clooney, 52, and Stacy Keibler, 33.

Their breakup had been a long time coming, with their relationship stuck in a gigantic rut in the last few months, according to Us Weekly. In fact, the couple was going through a dry spell without intimacy before parting ways. Needless to say, at least for the people closest to the now-former couple, they expected for both to call it quits.

[For the first story on their breakup, click HERE.]

"They hadn't had sex in months," a source told US. "He's been in Europe, and she's been in LA, and they haven't seen each other in a long time. Some girls would be okay with that and just be happy dating George, but not her."

Another insider said that Keibler "knew [Clooney] wasn't looking to get married, but there was always that fantasy that he would commit. And sadly, [their relationship] just ran its course."

Since they were clearly drifting apart, the twosome made a joint decision to breakup amicably. Linked together since July 2011, the two went public and made their official red-carpet debut at the Toronto Film Festival that Fall.

Keibler had been a constant in Clooney's life, sticking by his side at every high-profile Hollywood event from the Golden Globes to the Academy Awards. They also spent lots of time at "The Monuments Men" actor's Lake Como compound in Italy.

Reportedly, they will remain friends and stay on good terms.