(Cover) - EN Showbiz - Rene Zellweger took a back seat in her relationship with Bradley Cooper to try and make it work, according to reports.

Bradley Cooper and Rene Zellweger split because of his career, according to sources.

The Hollywood couple had been dating for less than two years when they decided to call it quits last week. A source close to Bradley, 36, has revealed the break-up was partly caused by the pressure of Bradleys pressing work commitments.

"If I had to pick any possible mistress it would be Brads career," the source told US magazine. "He worked really hard to get into leading man status.

The American actor who is famed for his roles in comedy hits The Hangover and The A-Team has been busy with his headline roles of late. His latest thriller Limitless topped US box offices this weekend, beating the likes of Rango, Battle: Los Angeles and The Lincoln Lawyer. Sources say Rene was happy to put Bradleys promising work commitments before their relationship, with the star even moving to be closer to her actor beau.

"Rene had to take a backseat. She travelled with him to make it work, an insider revealed. "She's accomplished a lot of her professional goals. So Rene took some time out to be a great girlfriend and see if this is what it took to make a relationship work."

The Hollywood couple had been dating for less than two years when they decided to call it quits last week. They met in the summer of 2009 and though they never officially confirmed their relationship, were often spotted out together. There were even suggestions of marriage between the couple. (C) Cover Media