After three years of dating, the CW's 'Vampire Diaries' co-stars Nina Dobrev and Ian Somerhalder have called it quits.

As an insider told Us Weekly their split will not affect the hit vampire show because the pair are "consummate professionals" and "will continue to work together and remain best friends, which is where the relationship started."

They first went public as a couple in 2011, but Dobrev was reluctant to get involved with a colleague in the first place.

"I didn't want to be dating one of my costars -- my goal on the show was to be professional, but sometimes you can't help who you have a connection with," Dobrev said last fall. "You can only fight it for so long -- which I did for a really, really long time."

Reps for the couple have yet to comment, but what we really wanna know is ... who gets custody of their cat?