Related : Mischa Barton Shares Why She Joined "The Hills: New Beginnings"

When it comes to her love life, Mischa Barton is staring at a blank page, and the rest is still unwritten.

The 33-year-old The O.C. alum and star of The Hills: New Beginnings and her Australian model boyfriend James Abercrombie have called it quits, E! News has confirmed.

"Mischa and James are over," a source close to Mischa told E! News on Friday. "The reason she broke up with him is to focus on her career."

"This is the first time Mischa is actually having a second life in her career, and she wants to focus on it," the source said. "That's the reason she broke up with him."

Mischa rose to fame playing Marissa Cooper on the drama series The O.C., and quit the show a year before it ended its four-season run in 2007. Since then, she has undergone some personal and legal turmoil, and her career has stalled; In 2009, she landed a top role in the Ashton Kutcher-produced drama series The Beautiful Life: TBL, but it was canceled after two episodes due to low ratings. Over the past decade, Mischa has appeared in mainly small films, and competed on Dancing With the Stars—an experience she described as "awful."

The actress made her big TV comeback in June as a new cast member on MTV's The Hills: New Beginnings, a reboot of the hit '00s reality show. In July, the series was renewed for a second season.