Kanye West is "jealous" of Taylor Swift.
The 'Stronger' hitmaker - who infamously interrupted the 25-year-old singer's acceptance speech at the MTV Video Music Awards in 2009 when she won the Best Female Video gong - reportedly "loses it" when people mention how successful she is.
A source revealed: "There's just something about Taylor that sends Kanye into a rage. He just doesn't get why she's so successful."
The 37-year-old rapper is believed to have "lost it" when he discovered her 'Shake It Off' video had received nearly eight times more views than his 'Bound 2' video.
A source shared to Star magazine: "He can't let go of a grudge, and it's never more apparent than with Taylor. If he hears her music or her name, he'll curse Taylor out as long as anyone will listen."
His "jealousy" is reportedly only getting worse now Jay Z has refused to include Kanye in his musical plans with Taylor, Beyonce and Justin Timberlake.
A source explained: "Kanye doesn't see things over his ego very often - if ever - and he is upset that he isn't in the club with Taylor, Jay Z, Beyonce and JT."
Taylors dislike of Kanye is believed to be so strong that "Jay Z doesn't want to ruffle any feathers with her by bringing Kanye into the fold on his Mount Rushmore idea."
However, the loss doesn't appear to be too upsetting for the 45-year-old rapper and music producer who is "moving on". A source shared: "Jay Z did his thing with Kanye and he is moving on to bigger and better things."