It's all over for Nicky Hilton and David Katzenberg. Due to conflicting, hectic schedules, the couple has split after four years of dating, insiders confirm to The New York Post.

"The main reason was that they have been busy with their work, and it has made it difficult to spend time together," a source tells the newspaper. "Nicky has been back and forth traveling overseas a lot with her business. She has recently been in Asia promoting her jewelry line, and David is starting a new production company."

Posted in: Nicky Hilton

Following three years of dating, the clock has hit zero for Kiefer Sutherland and Siobhan Bonnouvrier. This couple broke up earlier in the year, though word is finally spreading now.

"It's been awhile," a friend told Us Weekly of the split, though another emphasizes that the break could be temporary because the relationship is "transitional and ever changing."

Posted in: Kiefer Sutherland