WATCH: Kim Kardashian Calls Rob Kardashian and Blac Chyna’s Relationship ‘Unstable’

Thing between Rob Kardashian and Blac Chyna aren’t always all sunshine and rainbows. Though they’re currently expecting their first child together, the couple are still butt heads with each other.

In a new preview for an upcoming episode of Keeping Up with the Kardashians, Kim Kardashian admits her brother’s relationship with Chyna is a little “unstable” to outsiders.

“I know Rob and Chyna have an unstable relationship. There’s obviously two sides to every story, and they just know how to push each other’s buttons,” she says. “My brother just shuts down and doesn’t really tell us [what’s going on] because he doesn’t want us to turn against him or against her.”

“Instead, he just comes up with these excuses,” she adds, after she discovers that Rob has deleted all his Instagram photos because of a fight with his pregnant fiancée.

“Rob doesn’t realize that when he’s not in a good mood, it affects everybody,” Chyna laments during a phone conversation with Kim. “I just don’t want this to transpire to the baby.”

However, it already seems like Rob’s behavior is affecting more than just his family members. According to TMZ, the reality star is currently under investigation by the Los Angeles Police Department after he allegedly threatened to physically harm Pilot Jones, a man who was romantically linked to Chyna when she was on a break with Rob.

After a photo of Jones kissing Chyna surfaced online, Rob is said to have left multiple threatening text messages on the actor’s phone, including one that reads, “Leave my wife alone. I’m not playing with you.”

Sources claim other, more alarming texts exists, though another insider says Rob’s alleged threats are “a little murky and general” to be considered dangerous.

On Thursday (Oct. 27, 2016), Chyna took to Instagram to clear the rumors. Claiming that the kissing photos were taken over two years ago so Jones can make his boyfriend jealous, the Rob & Chyna star slammed her former friend for being an opportunist by selling the photos to a tabloid.

“Let me start off by saying this young man Is “GAY” !!! The only reason we took those pictures other than me trying to be a good friend was so he could send it to his boyfriend to make him like jealous & say that he’s going back to girls,” Chyna wrote. “Mind you at the time I THOUGHT THIS WAS MY FRIEND and I didn’t see a problem with it!!! This was over two years ago people !!!”

“I never had sex with him ! NEVER EVER! Nothing ever happened past these pics,” she insisted. “You just played yourself ! I would never fuck you ! Ur nasty ass fuck !”

Ok let's state facts !!! I been quiet for too long!!! So JC Pilot Jones whatever the fuck his name is has already tried to put out a story saying that he's the potential father of my child really Nigga ?!?!?! Let me start off by saying this young man Is "GAY" !!! The only reason we took those pictures other than me trying to be a good friend was so he could send it to his boyfriend to make him like jealous & say that he's going back to girls! Mind you at the time I THOUGHT THIS WAS MY FRIEND and I didn't see a problem with it!!! This was over two years ago people !!! I never had sex with him ! NEVER EVER! Nothing ever happened past these pics. Mind you if you really look at the picture, look at my right hand it doesn't have my "Future" tattoo next to that the fucking pictures was taken with the ring light!!! Staged Af! But now I understand why you put these pictures out ! Ohhh because you have a song with Trina you trying to get your fucking name popping ?!? Or are you mad at the fact that I did my Chymoji app without you dumbass JC ?!?? Your greedy ass wanted a cut of something that wasn't yours and u came at my lawyer asking for crazy money !!! U really mad ?!?! Like you really stooped this low ?!?! Coming for a Bitch that's due in a few days ! Really trying to start beef with my Fiancé !!! Your a fucking joke ! You just played yourself ! I would never fuck you ! Ur nasty ass fuck ! And everybody knows Chyna LIVES for the Community! But let's be for real … ur a dirty ass Punk !!!! You can never join my roster BITCH !!!!!!!!!!!!!!

A photo posted by Blac Chyna (@blacchyna) on