An eyewitness told ET that Rob was "sweet and so humble" at the shoot, while noting that the couple was constantly smiling and laughing. "The two definitely have a connection," the source said, adding that the two seem very comfortable with one another.
For her part, the 27-year-old model rocked her beach-side shoot, sporting a skimpy red-and-black bikini.
While supporting Chyna's latest endeavor, Kardashian admitted to the eyewitness that he was "not in the best shape and it was time to shave."
The sentiment falls in line with a newfound focus on fitness, which Chyna’s pal, Amber Rose, says has been inspired by Kardashian's lady love. "They're working out. Chyna's cooking healthy meals for him," the How to Be a Bad Bitch author revealed. "It's a really, really good vibe."