The pop superstar began dating Pete in May, shortly after ending her two-year romance with tragic rapper Mac Miller, and she stunned fans weeks later by confirming they had become engaged.
The couple soon set up home together in New York City, but it appears there's trouble in paradise - sources tell TMZ.com Ariana and the "Saturday Night Live" funnyman parted ways over the weekend (October 13-14).
Representatives have yet to comment on the claims, but the news emerges hours after Ariana pulled out of a scheduled performance at the F**k Cancer benefit gala in Los Angeles on Saturday.
According to E! News, her manager Scooter Braun had to apologise to the crowd after revealing Ariana wouldn't be gracing the stage as planned.
"Someone I'm very close to was supposed to come sing for you today, and because of things that she's going through, she couldn't be here today," he shared.
Comedian Trevor Noah stepped in to replace Ariana with a stand-up set.
The charity gig would have marked the "No Tears Left to Cry" hitmaker's first show since mourning the loss of her ex, Miller, who died from a suspected drug overdose in September, aged 26.
She bowed out of an appearance with Davidson at the 2018 Emmy Awards after the tragedy, with her representative stating she would be taking "some much needed time to heal and mend."
She also withdrew as the musical guest for the recent season 44 premiere of "Saturday Night Live", and has been candid about her emotional turmoil with fans online.
Last week (ends October 12), she hit back at a fan who called her "lazy," retorting, "Been thru hell and back and I'm doing my best to keep going (sic)."
She had also admitted she was having "a tough month."
"i'm trying to get my work done and get back to normal and it's hard and i'm human and tired," she wrote in response to a concerned Twitter follower.
Grande later added, "can i pls (please) have one okay day. just one. pls (sic)."