OK! EXCLUSIVE!! BRITNEY'S SINGLE AGAIN!

' boyfriend has pulled the plug on their relationship, sources tell OK! Model Isaac Cohen broke the news to Britney during a long-distance phone call on Sunday evening while she was in New York and he was in Los Angeles. 'They are no longer an item,' Brandi Lord, Isaac's agent at L.A. Models, confirms to OK! The pair met through Britney's choreographer and began dating in mid-December. It was the singer's first real romance since she filed for divorce from on November 7 last year. For a while Britney and Isaac were regular feature of the LA party scene. Last month they spent a romantic weekend together in a $40,000-a-night suite at the Palms Casino Resort in Las Vegas. With Britney, 25, in New York on business, Isaac has been staying with friends and caring for Snow White, Britney's teacup Chihuahua. According to a friend of Isaac, 25, he has been 'looking to get out of the relationship for a while. 'It was a bit much for him,' the friend tells OK! 'There was a lot of drama ? it was too much of a whirlwind. It wasn't one thing in particular. 'Her likes her. They had a good time together. He was doing his best to help her out ? but there is only so much one person can do.' What's next for Isaac? 'Hanging out with the guys and riding his dirt bike,' says the friend. 'He's focusing on his career ? working and going out on castings.' See next week's issue of OK! for more exclusive behind-the-scenes details of the sudden break-up, Britney's tears and how she is coping with being single again.