The 29-year-old sock designer and 28-year-old model, who share 3-month-old daughter Dream, recently ended their engagement for a second time, according to People.
"The wedding plans are off," a source told the magazine. "They are both trying to be mature about it. It was less dramatic this time."
"Chyna is super fed up with Rob and thinks he is way too emotional and depressed. She thinks he has terrible issues," the insider said. "He is always battling his own insecurities and is unstable. It's a major turn-off to her."
Us Weekly reported Kardashian and Blac Chyna's relationship has been on the rocks since their highly-publicized split in December. Sources said the pair are now living separately, with Kardashian remaining in their family home.
"[It's the same] with her yelling and screaming about how his family doesn't like or support her, and his insecurities," an insider said.
The Rob & Chyna stars had reconciled over the holidays after splitting in mid-December. The pair seemed the happy couple while bringing Dream to her two-month checkup and while celebrating their one-year anniversary in January.
"1 year down lol woohoooooo happy anniversary babbbbbbiiiiiiiieeeeeee," the new dad wrote at the time.
Kardashian and Blac Chyna got engaged in April after three months of dating and welcomed Dream in November. Rob & Chyna, their E! reality series, was renewed for a second season the next month.