However, it's Rob's "fragile state" that has the famous family concerned -- and it's also why the family hasn't been more publicly outraged about the relationship, the source close to the family says. Blac Chyna has various ties to the Kardashian family, not all of them being so friendly. The "Rack City" music video star used to be close friends with Kim Kardashian, but the friendship cooled after Kim's 18-year-old sister, Kylie Jenner, started dating 26-year-old rapper Tyga. Tyga is Blac Chyna's ex-fiance, and the two have a 3-year-old son together, King Cairo.
"The problem in this situation is no one wants to push too hard on Rob because of his fragile state," the source close to the family says, adding that Rob hasn't gotten his weight under control, and is still over 200 pounds. "Yes, Kylie feels betrayed, but she also doesn't see the need to publicly taunt him. If this relationship is good for Rob, even if it’s temporary, then Kylie is not going to push it. She'll get over it."
"The fear is that Chyna is doing this for attention," the source continues.
The 28-year-old reality star famously had a hard time dealing with his split from his ex, actress Adrienne Bailon, which was documented on Keeping Up With the Kardashians. The source claims Rob is still not over the former Cheetah Girls star, whom he dated from 2007 to 2009.
Surprisingly, Kim is unbothered by the situation, the source close to the family says, despite her formerly close friendship with Blac Chyna.
"Kim has no ill will towards Chyna," the source close to the family says. "Kim doesn't care at all. She has so much stuff going on -- losing weight, two kids, Kanye’s album. Rob and Chyna are the last of her problems."
ET has reached out to Blac Chyna for comment.
Meanwhile, Rob and Blac Chyna's relationship is showing no signs of slowing down. On Wednesday, Rob Instagrammed a close-up of his girl, captioning the photo with a key emoji.