Look out, world – Britney's single again. And the guy who dumped her, Isaac Cohen, says she's been "a bit much" for his taste. Britney got the bad news Sunday night, reports OK!,while she was in New York and Isaac was in L.A., -- over the phone. The pair had been together since mid-December, and Isaac was Britney's first boy since she split from Kevin Federline on November 7. According to a friend, Isaac has been "looking to get out" for some time, because it was "a bit much for him ... it was too much of a whirlwind." And now, speculates the mag, Isaac will resume his utterly anonymous existence, "riding his dirt bike" and focusing on "his career." As for Britney, it's back into the fishbowl for another catch.