Grande and the 19-year-old comedian first dated in August 2012 and were together for around a year before separating.
The 'Problems' singer felt Brooks was not supportive towards her, when she tried overcoming her grandfather's demise, reported Us magazine.
"It has not been an easy few months. Jai just wasn't as supportive as he could have been," a source said.
The 21-year-old star posted a message on her Twitter page yesterday asserting the fact some people had not been there for her while she grieved her grandfather.
"You learn a lot about love, life and the people around you during a time of crisis. 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 truly mattered.
"I thank everybody who was here for me when I needed them as the ones who weren't really broke my heart," she wrote.