Party pooper? Blac Chyna isn't pleased when Rob Kardashian skips out on her shindig in Rob & Chyna's Sunday, September 18, episode, as seen in Us Weekly's exclusive sneak peek.

The E! unscripted series' preview clip shows the pregnant makeup artist, 28, calling her fiancé, 29, to find out why he didn't attend a party at her home. The pair, who got engaged in April, butted heads in last week's series premiere when both accused the other of infidelity.

"What's the real reason you didn't come?" Chyna asks her man over the phone. "Not the reason you're going to tell me, but the real reason you didn't come today. Is it because of the argument?"

A somber Kardashian replies, "It's a combination of everything. I just didn't want you to see me and give you more reason to stop being attracted to me or whatever, so I just didn't want to go."

This clearly impacts the model, who tells the camera, "Even though I'm pissed at Rob for ghosting on me, when Rob says really bad stuff about himself, it kind of throws me off a lot because I don't see it. And I get it — everybody's down on themselves and has their opinions, but some of the stuff that he thinks and says is really sad."

A previously released clip from the episode featured Kardashian telling Chyna he was sorry about their fight, but that he wasn't ready to move back in with her.

Watch the emotional clip in the video above. Rob & Chyna airs on E! Sundays at 9 p.m. ET. 

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