The couple had been an item for about eight months; however Gomez, 19, apparently decided there was no future in standing by her man even though Bieber "insisted to Selena that the woman's allegations are simply not true," said a source close to the couple.
Bieber, 17, has been accused of being the father of a San Diego County woman's 3-month-old son. The woman, 20-year-old Maria Yeater, claims Bieber impregnated her during a backstage encounter.
Bieber has denied the allegations, but Yeater has asked a court to compel him to take a paternity test.
"His camp is in damage control mode and attempting to convince her to stick around in the relationship for a few more weeks, because they fear it will be seen as an admission that something indeed took place between Justin and the woman who is alleging that he's the father of her baby," the source told Radar.com.
Meanwhile, Yeater has another legal matter to address involving an ex. TMZ.com said Yeater faces trial in Las Vegas next month on a misdemeanor battery charge stemming from a fight last year with her own former boyfriend who she originally accused of being the father.