Kim Kardashian is upset with her older sister Kourtney for dating Justin Bieber, who is 15 years younger, Radar Online reported Wednesday. Kourtney and Bieber have allegedly been dating for days.

Kim called Kourtney a “disgrace” and that her rumored relationship was “lame and disgusting,” a source told Radar Online, according to Inquistr. "Kim has been begging Kourtney to think of the kids instead of constantly trying to get back at Scott Disick with all these 'look at me' outings and sleazy late nights with Justin and other young kids," the source added.

The insider also reportedly said that Kim was "grossed out to see this type of behavior from her big sister, of all people." Kourtney has three children with former partner Scott Disick.

While Kourtney reportedly began dating Bieber to annoy Disick, Bieber reportedly began the relationship with the 36-year-old because he considers older women to be “dominant.”

Nobody in the Kardashian and Jenner house seem happy with the relationship and her step-sister, Kendall Jenner, was trying to break Kourtney and Bieber apart, according to reports. And Jenner reportedly asked her model friend Hailey Baldwin to persuade Beiber to stay away from Kourtney.

Even Bieber's ex-girlfriend Selena Gomez, who reportedly confronted him over the matter, thought the relationship between Bieber and Kourtney was “incestuous.”