"They are no longer together but they remain close friends," Barton's publicist, Craig Schneider, tells PEOPLE. No third party was involved, Schneider adds.
While Barton's rep would not provide additional details about the split, a source close to the 19-year-old actress says, "It developed over the last week."
Davis confirms the split through his publicist Ken Sunshine, and tells PEOPLE, "I wish her only the best."
Barton began dating Davis, the twentysomething grandson of billionaire Marvin Davis, after the two were introduced at a charity event in February 2004.