The 31-year-old - who flew to Las Vegas to be with her estranged husband after he was discovered unconscious at a brothel in Nevada - reportedly decided not to attend her sister's 35th birthday celebrations on Wednesday and opted to stay instead with Lamar.
“Lamar isn't doing that well,”an insider told Us Weekly.
“He can't stand up by himself. She is still very worried about him and uncomfortable with leaving.”
Khloe - who split from her husband of four years in 2013 - was seen for the first time in over a week as she accompanied the star on his journey back to LA.
While Khloe didn't make an appearance, she did send a gushing birthday message to her sister on Instagram.
She wrote: "Happy birthday Keeks!! I pray you know how loved and dope you are!!! You continuously amaze me by how you do it all. Thank you for always being there for everyone! Today is about you!!! Enjoy it Mrs West!!! I love you, My bestie, my sister, my rider!"
Kim's birthday celebrations came on the same day that Khloe and Lamar dismissed their divorce case.
According to TMZ, the star is determined to help Lamar through his months of recovery and decided to drop the divorce after he insisted he was "done with drugs".
Insiders claim the NBA star pleaded with his wife that after hitting-rock bottom and cheating death, he is determined to get clean.