The two reportedly reconciled in last October, and have now gone separate ways, reports dailymail.co.uk.
A source told Entertainment Tonight that the 25-year-old brunette beauty, who underwent a kidney transplant last year, was "delicate" and the intense interest in her relationship with "Sorry" hitmaker Bieber and her mother had affected her.
"Selena is very delicate. Her 'comeback' to the spotlight has been tough - especially with the interest in her personal life with Justin and her mother. She is taking time to herself. This is not the first time she has done this," said a source.
"She wants to repair her relationship with her mother, that's a priority for her, too," the source added.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)