"She is with him now in Houston. She went to his game last night and bowling," the insider says. "They are still together and having fun."
The Keeping up with the Kardashians star and Houston Rockets basketball player began dating over the summer, but a second source says Kardashian's estranged husband Lamar Odom's health crisis has caused some tension.
"It hasn't been easy. James obviously has wanted to see her more and be with her in [Texas] more, but she's felt like she needed to stay in L.A. to be with her family and to deal with Lamar stuff," a source close to the family tells PEOPLE. "That has put some strain on things."
0Odom was found unconscious at a Las Vegas brothel Oct. 13 and has been hospitalized ever since, with Kardashian dedicating a large amount of time to supporting his ongoing recovery.
Kardashian, 31, previously told PEOPLE that Harden, 26, was "very supportive and awesome" as she attended to Odom.
VIDEO: Where Does James Harden Stand Now That Khloé Kardashian and Lamar Odom Have Called Off Their Divorce?
"I'm just allowing everything to unfold. If it's ever too overwhelming [for him], then I understand that as well," she said.
Kardashian and the ex-NBA star put their divorce on hold in October as they dealt with his health issues, though she told PEOPLE shortly after that does not mean they are getting back together.