"Khloe and James' relationship has taken a back seat at the moment," a source tells ET. "Khloe is really focusing on getting Lamar better and he is her number one priority right now."
Meanwhile, James is choosing to focus on basketball. On Monday night, the 26-year-old athlete played a game against the New Orleans Pelicans in Houston, Texas, his team winning by 20 points. And though he has stayed silent on Lamar's hospitalization, he hasn't been quiet on social media. James Instagrammed a billboard of himself on Tuesday, and this past Sunday, he Instagrammed a photo of himself with Houston Astros shortstop CJ Correa.
"He is so nice and being as supportive as humanly possible given the situation," a source tells People. "Lamar hasessentially has zero consistent family other than the Kardashians, and James understands that. The last thing he would want to do would be to add more stress to her plate."
Khloe and James appeared to be getting more serious in August, when she threw her beau a lavish all-white yacht party in Marina del Rey, California, for his 26th birthday. Almost the entire Kardashian-Jenner clan attended -- including Kim, Kendall, Kylie, Kris, and even Kanye West -- showing that the famous family was supportive of the relationship. A source tells ET that James was actually the first guy Khloe "really liked" after splitting from Lamar in December 2013.
"Khloe never loved [her ex] French Montana. He was a rebound and someone she had a good time with," the source says. "The first guy she really liked after Lamar was James Harden."
Khloe and James were first linked together in early July, when they were spotted partying in Las Vegas together. The pair showed PDA out in the open, and looked "very happy" and were "very affectionate" with one another, an eyewitness said at the time.
According to Us Weekly, Lamar was definitely upset about Khloe's new relationship.
"Lamar has been hating that Khloe is with James," a source told the magazine in August, after he reportedly "ambushed" Khloe in a parking lot. "Lamar wants her back. That's what stopped the communication on her end."
Lamar reportedly followed Khloe after a SoulCycle spin class in Beverly Hills in August, and allegedly launched into a verbal attack. According to TMZ, "Lamar was demanding that she talk to him. She kept walking." Khloe jetted to Houston to visit James after the incident, and the two were spotted at a Chipotle together.
"Lamar and I loved each other deeply, and I don't believe in just acting like that relationship never existed," Khloe explained. "Things happened, but that doesn't just stop me from caring about him or loving him."
"This past week has been incredibly difficult. I am so thankful to family, friends and fans who have sent nothing but prayers and well wishes to Lamar," Khloe wrote on her website and phone app on Tuesday. "You can never be prepared for an experience like this, but without the outpouring of love and endless prayers that Lamar has received and the strength I was given from my loved ones, it would have been difficult to endure. Thank you for your continued support. God is great!!"