The five year age difference between Drew and Fab may have been behind some of their problems. A friend of Drew's told Us, "He's younger, and she's more worldly. He doesn't like the Hollywood stuff. He doesn't get her friends.

The split may not be permanent, though. Moretti and Barrymore have ended things before, but wound up back together. The source says, "This is exactly what happened last time they took a break."

Barrymore, as usual, was the initiator of this particular break up. A source close to her said, "Drew said they needed time off." Don't expect the split to be too short-lived, though. One of Moretti's friends said, "Fab is now living back in his old apartment." It will probably take at least a week for him to move his stuff back into Drew's place again, right?