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Kim Kardashian is speaking out about her brother Rob Kardashian's relationship with Blac Chyna in a new clip from this Sunday's episode of "Keeping Up With The Kardashians."

"I've always felt that them as a couple isn't healthy," Kim said. "Rob can be very irrational and he just needs to learn to take responsibility for himself and not blame it on Chyna. This just, like, all has to stop."

"It's so clear what this relationship is," she said. "They're just not meant to be with each other."

After Rob and Chyna had an explosive fight where Chyna ended up leaving, Rob vented on social media in an emotional set of Snapchats which Kim Kardashian said "is really not like him."

Immediately following the fight, Rob sat down with Kim and Corey Gamble to talk about what happened.

"I wanted people to know I'm hurt, this is f--ked up," he said, "the fact that you say 'If he doesn't have his shit together in a year I'm gonna drop him,' like who are you to say 'I'm going to drop you?'"

Rob then said that he was confident that Chyna was not going to come back to him.

About Chyna, Kim said, "I've always been super cool with her. I have a different relationship with her but just seeing the motives is what's hurtful."

"Keeping Up With The Kardashians" airs Sundays at 9 p.m. ET/PT ON E!