Nicky Hilton and David Katzenberg call it quits

Nicky Hilton and David Katzenberg © Alexandra Wyman/WireImage

Nicky Hilton and David Katzenberg have split up, according to New York Post's Page Six. A friend tells the newspaper, "They broke up quietly after four years together. The main was that they have been busy with their work schedules, and it has made it difficult to spend time together." The friend continues, "Nicky has been back and forth travelling overseas a lot with her business. She has recently been in Asia promoting her jewelry line, and David is starting a new production company. Their schedules never seemed to match."

Nicky, 27, and David, 28, "remain close friends. They have been friends since they were teenagers." Nicky has been leaning on sister Paris after the break up from the The Hard Times of RJ Berger creator. She is quoted by US Magazine as saying, "Paris has a house in Malibu, so I've just been spending time relaxing there. Paris and I are going to go to the South of France next week for some business and pleasure."