Their joint statement doesn't reveal much about what went wrong, stating: "They both care deeply for each other and remain close friends. We kindly ask that the media respect their wish for privacy regarding this personal matter at this time."
A source tells Us Weekly, however, that their busy schedules may be to blame, noting: "They made the decision to part ways because their conflicting touring schedules would keep them apart over the next year."
Of course, there's a bit of buzz that Justin Bieber's handsy performance with Ariana earlier this month may have been a cause of the split. At the time, Big Sean was believed to have threatened Justin on Twitter, but his rep assured it was a fake tweet.
UPDATE: As we expected, the rumor that Justin was to blame for Ari and Big Sean's breakup is so false, with Gossip Cop reporting that "a source close to the situation" says the claim is "laughable" and that "They are all still good friends."