People magazine reports Tony Romo broke up with Jessica Simpson on Thursday, the night before her 29th birthday.

"She is heartbroken," says People's "source" on the matter. "She loves Tony. But it's been difficult lately. He's busy with his career and she's getting ready to shoot her show (The Price of Beauty). They decided to part ways."

The Dallas Cowboys quarterback fueled breakup rumors when he showed up with about 14 friends at the Hollywood hotspot MyHouse on Friday night without the birthday girl.

"He had quite a few girls stop by his dance floor table," says an onlooker. "Romo was sipping Grey Goose and having a fun time with the boys."

Simpson's rep had no comment. Romo's rep could not be reached for comment.