Blac Chyna & Rob Kardashian. Picture: Instagram

Rob Kardashian and Blac Chyna have reportedly split up again after failing to get their romance back on track.

The 'Keeping Up with the Kardashians' star and the 28-year-old model, who share three-month-old daughter Dream, decided to end their engagement after failing to get their relationship back on track following their brief split in December.

A source close to Rob, 29, told Us Weekly magazine: "Rob thinks it's the right decision. Chyna has disappeared for days at a time without communicating or providing any updates. This won't end well."

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Another insider said the couple, who have been living apart since their initial split before Christmas, have been struggling to get along over the past few months, adding: "[It's the same] with her yelling and screaming about how his family doesn't like or support her, and his insecurities."

The pair, who first split after they got into a bitter war of words on social media in December and rekindled their relationship when Rob publicly apologised, are still filming season two of their E! reality series 'Rob & Chyna'.

Rob's mother Kris Jenner recently hinted the duo's romance was often tumultuous.

Speaking about the pair - who got engaged after four months of dating - she explained: "You know, I think that, too, is a work in progress and they have good and bad days. It's a young relationship and they haven't known each other for that long."