The 22-year-old singer and Kemp, a pro baseball player with the Los Angeles Dodgers, became an item in January.
Kemp seemed perfect for her and was a steadying force in her life after her rocky relationship with rapper Chris Brown ended in a horrific assault on the eve of the Grammys in 2009.
But Rihanna’s hectic schedule and Kemp’s longing for a more normal existence apparently helped kill the romance.
“He just can’t keep up with her crazy travel schedule,” a source told Us Weekly, which broke the story.
“Matt’s sick of always following after her like a puppy dog all over the world. He wants something more normal,” the source adds.
“She basically was just over it,” the source said.
The couple was also plagued by cheating rumors earlier this month. But the relationship may already have been over by then.
‘Just had dinner w/ Simon Cowell Philip Green, and Lucian G., and Ashley (thanks) @ Sandy Lane! Great night!’ she tweeted.
Rihanna and Christina Aguilera caused an uproar in the UK after giving racy performances on Cowell’s show “X Factor,” the UK equivalent of “American Idol.”
UK TV regulators launch an investigation into the show after a slew of complaints the performances were too risqué for family television.
Rihanna spent Christmas with her family in Barbados before jetting back to the United States for New Year’s Eve.