The couple had flown to Mexico to celebrate New Year's Eve together but they had an argument that caused the breakup, a source said, reported Aceshowbiz.
The 20-year-old actress flew out of Mexico on December 30, while the Canadian crooner opted to leave the following day. The source said that the couple are yet to see each other since their fight.
18-year-old Bieber's relationship with the Disney starlet has been on thin ice since November, when they first called it quits.
The couple has tried to make things work, however, stress from the pair's relationship appears to be taking a toll on Bieber's career.
An insider had earlier said that Gomez had been giving Bieber a really hard time by partying without him, which is driving him crazy.
