Khloé Kardashian is reportedly "frustrated" at Rob Kardashian for dating Blac Chyna.

Khloé Kardashian

Khloé Kardashian

The 'Keeping With The Kardashians' star is said to be fuming at her younger brother for dating her stepsister Kylie Jenner's boyfriend's ex-partner and "disrespecting" the whole family in the process.

A source told PEOPLE magazine: "She has gone out of her way a million times to help him. She always defended him. She was frustrated by his lack of respect."

Meanwhile, the Kardashians and Jenners are growing "concerned" for the 28-year-old sock designer after Blac was arrested for drug possession.

An insider said previously: "[At first], it seemed Blac Chyna was really encouraging Rob to stay healthy and clean. But her arrest is changing things. The drug possession is very concerning.

"No one wants Rob to live with someone who does drugs. If [Blac Chyna] isn't helping him, Rob's family won't tolerate it."

And now Khloé, 31, is feeling "majorly betrayed" by the whole thing as she always provided a home for Rob.

A source said: "Rob is living with Blac now that Khloé kicked him out after finding out about him and Blac. Khloé feels majorly betrayed by Rob after she always stuck up for him. She feels like this is a major blow to the family. Nobody in the family likes it."