"The initial dramatic and shocked reactions from Rob's family have actually calmed down a bit," a source tells PEOPLE. "It's difficult to not be at least a little bit excited that Rob finally seems to have snapped out of the funk. Everyone agrees that he deserves to be happy."
Indeed, Rob, 28 – who in the last two years has remained out of the public eye and away from the Keeping Up with the Kardashians cameras while battling depression and significant weight gain – seems to be making changes in his life: On Thursday, he posted a picture of himself working out.
"He acted miserable for so long. It was awful when he just wanted to isolate himself," the source says. "It was sad that he was embarrassed about his weight gain and got depressed. Forever it seemed like Rob wasn't mentally able to snap out of it."
While it's "definitely very annoying that Chyna is the one that could get to him, at least Rob seems happier," says the source. "It's still frustrating for his family that they tried to help him for so long and he wanted nothing to do with their help, but at least his family gets a bit of a break."
After Rob was hospitalized in December (and later diagnosed with diabetes), he continued to be destructive about his health, which was "very frustrating" for his family, the source says.
"Now he seems to do what's best for his health," the source continues. "If he works out with Chyna and eats healthy, that's a very positive thing. If she can get him to feel more comfortable and not embarrassed, that's a huge step for Rob."
Another source tells PEOPLE that the formerly reclusive reality star has been out and about with Blac Chyna, 27, "every day."
"He already looks transformed. He acts very happy, confident and keeps smiling," the source adds. "It's like a new Rob."
News of the romance, which broke on Monday, initially created major waves within the family due to Blac Chyna's long and difficult history with the Kardashian-Jenners: She was previously close with the famous family, particularly Kim Kardashian West, though the friendship dissolved after Blac Chyna's ex-fiancé Tyga, which whom she shares a son, started dating Kylie Jenner, 18.
Sources told PEOPLE earlier this week that Kylie was "livid" and that Khloé Kardashian felt "very betrayed."
Now, however, "there is no doubt that Chyna so far seems to be a good influence," the source says. And on Friday, Rob's mom Kris Jenner was spotted arriving at Blac Chyna's home in Los Angeles, where Rob is living. (On Wednesday the new couple also visited Kris at her house in Calabasas.)
"They're working out," she said on Friday's Allegedly podcast. "Chyna's cooking healthy meals for him. It's a really, really good vibe. ... Rob is the coolest guy you'll ever meet in your life. He's realistic. He's just an amazing person, and it's sad that people don't really get to see that. But he's just down to earth and just cool."