"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.

"He 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."

"They are no longer an item," Brandi Lord, Isaac's agent at L.A. Models, tells OK

Star claims, male model Isaac Cohen, 25, dumped Britney Spears by cell phone.

"Isaac told me he called up Britney on her cell on Sunday while she was in New York and told her he wanted to end the relationship," says Yaniv Fituci, who directed Isaac in the music video Hinterland by DJ AIM - where Isaac was, of all things, chasing a dollar bill. "Their schedules clashed. He wanted to stay in Los Angeles for acting opportunities and she had to fly all over the place, like Las Vegas and New York."

Still, Yaniv thinks Isaac was a great influence on Britney Spears.

"He toned her down for sure. Especially when they were in Vegas. There were a few nights where he told her to take it easy. One night he made he go back to the hotel early because he had an audition in L.A. the next morning and needed some sleep — he's very professional — and she complied."

"They were a good item while it lasted, but it was never really that serious, it was more of a fun thing. Isaac is a fun person to be with, he's a great guy and makes everyone laugh."