Ian Somerhalder and Nina Dobrev have split up.

A source told Us Weekly that despite their split, Ian, 34, and Nina, 24, are "consummate professionals" and "will continue to work together and remain best friends, which is where the relationship started."

The couple met on the set of the hit US TV show - in which Nina plays Elena Gilbert, a high school student torn between vampire brothers, Damon (Ian) and Stefan (played by Paul Wesley) - in 2009 but they didn't go public with their relationship until 2011.

Nina recently admitted she didn't intend to date where she works, but couldn't resist her feelings for her hunky co-star.

She said: "I didn't want to be dating one of my co-stars -- my goal on the show was to be professional. But sometimes you can't help who you have a connection with, and you can only fight it for so long -- which I did for a really, really long time."

The former flames will avoid any awkward encounters in the immediate future as the fourth season of 'Vampire Diaries' has already wrapped production, but they are expected to return to the show's Atlanta, Georgia set in July for filming of the fifth season.