The 21-year-old singer and 19-year-old YouTube prankster were previously together from August 2012 to July 2013, and reconciled in May this year. A source tells E! News Grande ended the relationship in July.
"When her grandfather was dying, everyone was there for her," the insider reveals. "People flew to Florida to be with her, but Jai didn't. Ariana just felt he wasn't there like he should have been."
Grande's grandfather died of cancer July 22, a loss the singer said was "the hardest thing imaginable." She took to Twitter on Monday to commemorate her grandfather once again, and the source says part of her post is directed at Brooks.
"You learn a lot about love, life & the ppl around you during a time of crisis," Grande wrote. "July was painful for many reasons but of all the personal loss I suffered last month, the loss of my grandfather, a true gentleman, was the only one that mattered."
"I thank my loves for being so in tune to what is good and right for me and my heart," she continued. "I hope you will surround yourselves with people who will be there for you thru the bad times, not just the good. I thank everybody who was here for me when I needed them as the ones who weren't really broke my heart."
Grande will release her second studio album, My Everything, on August 22.