The 31-year-old says they've always been the closest out of all of their family and she's was always there for him - even in his darkest moments - and when no one else was.
In the opening scenes, Khloe and Kim are discussing Rob getting a new house.
"I’m the only one that stood by him and defended him and wanted the best for him. This is where it gets frustrating," a disappointed Khloe admits.
"They were really close in age and they were BFFs. They live together. They have such a history together so I think Khloe is just extra hurt that he still hasn't called her since he moved out. But I understand it and I really do feel bad for her."
Khloe also talks to Kris about Rob's house, and wants to know where the once-reclusive star got the money from to afford it.
"He has the money for the down payment," the momager insists. "Why are you so angry all the time?"
When the 31-year-old tries to stifle a cough, Kris asks: "Do you have a cough?"
I’m just allergic to bulls**t," Khloe, who was noticeably absent from Rob's big family birthday meal at the end of March, hits back.
The reality star then admits she's annoyed that Kris is helping her brother after all the stick she got for doing the same, and says she isn't going to congratulate him because she hasn't spoken to him.
"I would have such deep fights with my family because I was ‘enabling' Rob by letting him live with me and the one person that would yell at me the most was my mum, and now she’s buying him a home," she tells camera.
"I just find it mind blowing."
“I hope he’s thanking you," she tells her mum.
“Yes, he did yesterday I thought he was going to cry. He was so sweet. I want you to see the house."
“I will whenever he feels like inviting me," she replies. "You don’t think it’s weird that Rob hasn’t called me one time?”
"I don’t think it’s weird. I think it’s certainly disappointing for you and I would want him to call me too but I think you guys just see this whole thing differently.
Khloe fires back: “What would he hold a grudge over? Me taking care of him for six years?"
"Boys are different and he’s very sensitive. I didn’t realise how sensitive he is, and I think he loves you very much," Kris replies.
Khloe, who also refuses to let Kris use her assistants to help with Rob's move because he's "inconvenienced" her life enough, continues: "He shows it.”
To camera, the upset star adds: "What I’m so confused about is why he has such issues with me all of a sudden.
Elsewhere, Khloe vents her anger to her BFF Malika Haqq.
“I guess you’re not going to send him a house warming gift? Do you even talk to him?”
“No. He should be sending me one. He hasn’t called to check on me or say hi or I miss you. He’s lived with me for how many years and he’s just OK to completely leave and not say a thing to me? It shouldn't be OK for people to leave that easily."
"I’ve always been by Rob’s side and loyal to a fault so I never imagined out of any sibling he would be able to cut me off the way that he has."
The show ends with Khloe trying to call him but he doesn't answer and when she eventually pays a visit to his new house to try and clear the air, he's not at home.
However, it looks like the pair have since made up after Blac Chyna revealed her baby news.
Late last month Khloe shared a series of Snapchat videos of them both holding hands.
