More details on the Justin Bieber and Selena Gomez break up are beginning to emerge, with a source close to both stars citing their hectic working schedules as the reason for the split. News of Justin and Selena's break up hit the web over the weekend, though they're understood to have gone their separate ways about a week ago.

An insider told E! News, "Because of their crazy schedules, it was getting harder and harder to maintain a relationship," which seems fair enough. Bieber has been touring almost nonstop over the past few years, while Gomez has also been busy with her various commitments. It hasn't stopped fans speculating as to other reasons for the break up and Bieber was spotted seeing The Lion King on Broadway this week with a group of friends that included Victoria's Secret model Barbara Palvin.  Bieber and Gomez first went public with their romance in February 2011, attending the Vanity Fair Oscar party together, though Gomez began receiving hateful messages on Twitter almost immediately. "It hurts, it really does," she told Z100 radio in New York, "I don't feel like I'm doing anything wrong. I've been best friends with him for a very long time. It does hurt my feelings a lot, but I try not to focus on it."

It's likely that further details on the split will emerge in the coming weeks. The Huffington Post certainly aren't convinced by the 'crazy schedules' line, cryptically tweeting, "We have a feeling there's more to Selena Gomez and Justin Bieber's breakup than meets the eye."