The Kardashians found out Rob proposed to Blac Chyna online.
Khloe, 31, Kim, 35, and Kourtney, 37, were on holiday in Vail, Colorado when they found out the news that their brother had got down on one knee.
In scenes aired on Sunday night's (19.06.16) episode of 'Keeping Up With The Kardashians', Khloe said: "He proposed in front of her whole family. That's so f***ed up. Rob is such a p***y. I'm not going to cover for him anymore. What am I covering for him anymore for?"
Whilst Kim added: "I don't care if he tells me, I truly could care less."
But sibling Kourtney called them both out, telling them: "Maybe he thinks that you guys are judgmental because clearly you are ... That's exactly why he didn't tell you, because you're a b***h [Kim]."
And Khloe then told the group: "Instead of sharing this with his family he keeps pushing us away. Is someone in his ear giving him this information that he should stay away from us?"
Meanwhile, earlier in the episode, the family were less than impressed when Rob - who is expecting his first child with Blac - refused to come on the holiday incase Blac's ex Tyga - who was dating Rob's stepsister Kylie Jenner at the time - would be coming along.
Kris Jenner said: "It makes me so sad, and making another memory without him breaks my heart. This would have been really great for him to connect with the family again."
Whilst Kim added: "It's just a different dynamic when he isn't around. It's just sad. We want memories with him."
And Kourtney appeared to have her brother's best interests at heart and spoke of her hope that he could reconnect with his family again soon.
She shared: "I think that Rob has his happy life with Chyna. But I just hope that it gets to the place where he wants to hang out with his family again."