The 20-year-old singer-actress and the 18-year-old 'Baby' hitmaker - who went public with their relationship in February 2011, broke up about a week ago. They were last spotted together on October 20, reported E! online.
"Because of their crazy schedules, it was getting harder and harder to maintain a relationship," a source said.
The news comes after Bieber was seen chatting with models backstage at the Victoria's Secret show. The 18-year-old pop star also took 19-year-old Hungarian fashion model Barbara Palvin to see The Lion King on Broadway.
Amongst claims they split last week, Gomez angrily posted a picture on her Twitter page showing Bieber with his rumoured new girlfriend in the background a day ago.
The text the 20-year-old posted alongside it was a mysterious, '...'.
It has emerged that the fashion model attacked the 'Wizards of Waverly Place' star earlier this year.
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In a webchat 11 months ago she offered to sing her fans a song of their choice, but added, "I don't like Selena Gomez by the way..."
Palvin was also not shy to post images of her and Bieber at the high profile fashion show, and next to one where she is in her dressing gown with him, she said, "Okay so because you guys were asking for it with @justinbieber! you were great tonight."
She also posted an image where she is posing with Bieber's manager Scooter Braun and director Alfredo Flores.
Gomez also seems to be moving fast.
She tweeted a cosy snap of herself lying down next to British star Gregg Sulkin as they filmed until the early hours of the morning on location in Hollywood, where they are shooting their "Wizards Of Waverly Place" reunion movie.