And while it appears as though they kiss and make up after every screaming match, a source close to the situation has since revealed that tension between the pair continues when the cameras stop rolling!
"They can't be in the same room together," a well-placed insider told Radar Online of their strained dynamic. “Kourtney has hated Kim for a couple of years now. She thinks she’s vapid and mean."
“Their egos have clashed big time and when the cameras aren’t on, they don’t speak, “ the source continued. “There are hints of their feud, of course, but the reality is they genuinely can’t stand each other.”
While the source claims Kourtney "has much better things to do with her time than kiss up to Kim," the KKW Beauty founder believes her older sister should appreciate her more, seeing as Kourtney would "be nobody without her".
WATCH: Kim Kardashian Calls Kourtney a 'F***ing Fake Humanitarian Hoe'
Niall Horan's three-year text message prank on Fitzy
Disney's Mulan | Official Trailer
YOU Season 2 | Official Teaser
Criss Angel's son in hospital after cancer returns
Bec Judd sends nanny off to twins orientation while she partied
Meghan Markle dazzles as a ‘Briefcase Babe’ in Deal or No Deal
Kim Kardashian reveals new 'cozy' SKIMS PJ's and lounge wear
MAFS' Ines calls Potts Point the 'most disgusting place in Australia'
Ada Nicodemou and Adam Rigby cuddle up at the AACTA Awards
Tension reached boiling point between Kim and Kourt last week after the mum-of-four accused her sister of being "ungrateful" and "stealing her style".
“Kim and I just got into the biggest fight,” the Poosh founder told her friends during last week's episode. “She just was going so crazy, she’s sending me the meanest text messages. You would die.”
“She’s like, ‘You’re the biggest, ungrateful bitch,’” Kourtney read from her phone. “So I said, ‘God, you’re such a petty woman.’"
Meanwhile, Kim unloaded to her mum Kris Jenner about their brutal screaming match.
“She just is such a bitch, like on another level,” Kim said. “Kourtney screamed at me on the phone. And was like, ‘You think I like your style? You have the lamest style.’ “
Things took a turn for the worse when Kourtney slammed Kim's "terrible attitude".
“You’re going to school to become a lawyer and help the world and these are the kinds of problems you have?” Kourtney said before reading Kim’s response. “Then she’s like ‘You’re really a miserable human-being and you keep not understanding the issue because you all of the sudden turn into such a humanitarian and talk about the world’s issues which you’ve not contributed one ounce to the world.'”
Kim them threw the lowest blow of them all.
“I actually do s**t for the world and you f**king fake it all day long and act like, ‘Oh! There’s people dying, Kim.’ And what the f**k are you doing about it? So, shut the f**k up.”