Rob Kardashian has "no filter"

A source revealed: "The show is going to be amazing. Rob has no filter and he's so upfront. It's going to be great TV."

A TV crew is following the 29-year-old star as he and the 28-year-old model prepare for the birth of their baby and their upcoming nuptials.

Rob used to suffer from depression and refused to speak to friends and family, but his life has changed for the better since meeting Blac and he is "excited" about his future with the beauty.

The source told PEOPLE: "Rob is finally excited about life again, Chyna makes him so happy. It had been so long since Rob had smiled. Rob used to be such a goofy guy. Now that's coming back. He has a reason to smile again."

And his famous family believe Blac - who already has four-year-old son King Cairo Stevenson with her ex-boyfriend Tyga - "saved" his life.

A source said: "Khloé had the most issues with the relationship. She found Chyna in her kitchen [when she started dating Rob] and didn't know what was going on. She felt very disrespected.

"The girls literally thought Rob was going to die. They feel like Chyna saved him. The [Kardashian sisters] have gotten over their issues with Chyna now. They've welcomed her in."

Despite their approval, Rob's family found out he'd got engaged online whilst they were holidaying in Vail, Colorado.

In scenes aired on Sunday night's (19.06.16) episode of 'Keeping Up With The Kardashians', Khloe said: "He proposed in front of her whole family. That's so f***ed up. Rob is such a p***y. I'm not going to cover for him anymore. What am I covering for him anymore for?"

With Kim adding: "I don't care if he tells me, I truly could care less."