On this Sunday's episode of "Keeping Up with the Kardashians," Kris Jenner admits to Kim that she stays up at night crying over Rob Kardashian and his depression.

Rob Kardashian has been the topic of tabloids for his weight gain, disheveled appearance and skipping out on Kim Kardashian's wedding with Kanye West.

At the time of Kim's wedding, many reports, including one from one from X 17, cited Rob's weight gain and disapproval of his family's over-the-top lifestyle as the reasons for his depression.

"Rob said he was sickened by Kim and Kanye's display of wealth and clothes and beauty and called it 'superficial bullsh*t' but Kim was pissed that Rob hadn't made an effort to drop any weight over the past few months," said an X17 source at the time of the Kim-ye wedding. "Rob basically thinks Kim cares about him only for his appearance and he said he'd 'make life easier' for her and just leave."

Despite reports of the Kardashian family putting pressure on Rob to lose weight, Kris expressed a very different attitude towards her son in the latest "KUWTK" clip, according to E! News.

"I want to fix Rob and sometimes you just can't. I have not not cried myself to sleep in so long that I don't even know what that's like," Kris admits to Kim during their family vacation in Thailand.

Kris then begins to cry over the fact that Rob ditches the family vacation and opts to stay at home instead.

"It's the worst feeling in the world when one of your kids isn't in a good place," she continues. "You don't think it's torture for me to be here in Thailand and have him at home?"

Check out the emotional clip below.

To learn more about what Kris has to say and what happens to Rob during the family's vacation in Thailand, watch this Sunday's episode of "Keeping Up with the Kardashians" on E! at 9/8c.