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Justin Bieber and Selena Gomez are officially OFF (again) - this according to Us Weekly magazine, who reports the pair have ended things for good this time.

PHOTOS: Bieber and Gomez in happier times

It looked like Bieber and Selena had rekindled their romance,  spending the weekend before Christmas skiing in Utah (with then-smitten Harry Styles and Taylor Swift), and then jetting off to Mexico to spend New Year's in Puerto Vallarta. But the pair didn't ring in 2013 with a midnight smooch - according to Us Weekly, Selena left Mexico early December 30 for LA after a huge fight with Justin.

A source tells the magazine, "They had another huge fight, and Selena won't forgive him."

On New Year's Day, Gomez tweeted, "New beginnings. Fresh start. I love you all :)"

As for Justin... "He's been really down about the breakup," a source admits. While Selena was with friends at a party, Bieber spent New Year's Eve flirting with ladies at an L.A. club with his pal Lil Twist.

Last week, the Biebs was caught on camera smoking something that was not a cigarette, and rumor has hit his upcoming acoustic album will shed some light on the break-up.

READ MORE: Us Weekly