Kim Kardashian: 'Brother Rob’s relationship with Blac Chyna is not that healthy'

Kim Kardashian has feared for months that her brother's on-again, off-again romance with Blac Chyna is doomed.

The 36-year-old shared her feelings about Rob’s tumultuous relationship with new mom Chyna after she stormed off with the couple's baby daughter Dream following a quarrel last year (16) - and her comments feature in a new episode of the family's reality show Keeping Up With the Kardashians.

In a promo clip, Kardashian and her mother Kris Jenner’s boyfriend Corey Gamble, visit Rob at his home to check in on him after the break-up.

"We're all worried about Rob, so I brought Corey with me to Rob's house just to see what was going on," the star says, before her 30-year-old brother admits to being “hurt” by Chyna and questions her true feelings for him.

As the cameras roll, Kim agrees with her brother, despite her friendship with the model, revealing she believes the 28-year-old’s motives are questionable.

"I've always been super cool with her," she says. "I have a different relationship with her than what guys have... and I always hear her out and stuff. But just seeing the motive is hurtful."

In an excerpt from a confessional interview, the mom-of-two also shares her thoughts about the couple’s troubled relationship, calling it unhealthy.

"I've always felt like them as a couple is just not that healthy, and I think they know it too," she says candidly. "It's not just like some secret. It's so clear what this relationship is, and that they're just not meant to be with each other."

Rob and Chyna began dating in January, 2016, and they became engaged just four months later in early April (16). It is unclear if their engagement is still on as the pair have broken up twice since the news was announced.

The couple welcomed its first child, Dream, in November (16).