Are Jennifer Aniston and John Mayer over already?

Aniston is already dating someone else in Los Angeles, the New York Daily News' Rush and Molloy column reports.

The U.K.'s Daily Mirror reports that the "Friends" actress, 39, was dumped by the singer, 30, after the pair initially decided to spend some time apart ... before making the break official earlier this week.

"There's been a bit of tension for some time," a source close Mayer reportedly told the Mirror. "They initially opted for a break, hoping a trial split might make them stronger. Sadly it doesn't seem to have worked. John took the decision to end things as he felt he just wasn't ready for the level of commitment that Jennifer deserved.

"Contrary to reports, Jen didn't want to have kids or marry this year, but she did want to set a timetable for their future together. She also wanted him to assure her he would cut down his tours in the future when they did eventually have children.

"Initially, Jennifer was furious when he told her of his decision but now she's simply sad — not to mention a little heartbroken."

They have spoken on the phone since the split and are trying to remain on good terms, the Mirror reports. "But unless John has a dramatic change of heart, it's unlikely they'll rekindle their romance," the source said.

Aniston divorced Brad Pitt four years ago; Mayer was previously linked to Jessica Simpson.

Click here for the Daily News report

Click here for the Daily Mirror report