A source told PEOPLE magazine: "Khloé supports Lamar financially in every way. Khloé is very worried about Lamar and his behaviour. But Lamar refuses to listen to her.
"He actually said to her, 'Nothing will happen to me. Look how I survived the last time.'"
Earlier this week, following what appeared to be a happy Easter weekend spent with Lamar and her family, Khloe shocked fans with a cryptic tweet.
"I hate this feeling... Helpless," she wrote.
Meanwhile, the 31-year-old television personality recently revealed they're definitely not back together.
"I still believe in my vows of being there for him. I know it's confusing. it's very confusing. It's not a romantic place. It's coming from a place of real care and concern and love.
"I don't think love just because we're not romantically involved means I can't care about someone. I find that so simple-minded."