And on last night's episode, the 29-year-old got very emotional discussing his behavior.
While on a road trip with step-dad Bruce Jenner, sisters Kendall and Kylie, brother Rob, step brothers Brody and Brandon, and Brandon's wife, Leah, the reality star received a strange phone call that revealed her athlete husband is missing.
"I've been down this road probably way more times than I'd like to admit," she told E!'s cameras. "If someone wants to leave, they want to leave."
Khloe then admitted she'd reached her limit with him.
"You're not my child, I can't lock you in a room – as much as I would like to," she said to the show's cameras, adding that his behavior has been "weird."
Before heading out on the family trip, Bruce wanted to camp in the desert and expressed that he wanted Lamar to come along. Khloe would later hijack the trip and take the family to Area 51 in Nevada to go alien hunting.
"Lamar does NOT do outdoors," Khloe told Bruce.
"Lamar's the toughest one," he said. "We need a tent that's extra-long, and an extra-long sleeping bag so he'll fit in."
Khloe then said in a confessional segment, "Even though I don't like camping, right now I need all the distractions I can get. They're kind of like therapy for me."
She never outright talked about her husband's alleged drug addiction, but it was easy to see how the topic directly hit close to home when the family discussed the recent drug-related death of Glee actor Cory Monteith.
After Khloe asked Bruce, "Do you think it was a choice?" Bruce was very vocal about his beliefs, saying, "I have a hard time with people that need drugs to have a good time."
"You know being a drug addict is a disease," Khloe said. Bruce responded, "No. It is a personal choice. You know what you're doing? You're taking the responsibility away from the person"
“This guy had a choice to take drugs,” Bruce said of the Glee actor. “It’s his own fault. You can’t blame anybody else but him!”
Lamar finally got in touch with Khloe while in the family's motor home on the way to their trip.
"You feelin' okay?" she asked her husband. "So-so?"
She revealed to the E! cameras: "Lamar has been having a really hard time lately. It's not just black and white. There's a lot of emotional issues and as much as I'm trying to enjoy going camping with my family, I also have to cater to Lamar's needs."
She said, "It's really scary when nothing's really working, and then you know if you give up no one in his life would be able to help."
That wasn't the last time they talked. He called her again when she was sitting around a campfire with the group in Nevada. Lamar followed up that call by dialing Bruce.
"He just wants to see that you're with him, "Kylie told Khloe.
Lamar hung up, but then called Bruce again. He handed the phone to Khloe – but Lamar already hung up.
"Call ended!" she said. "He hung up on me!"
But he called Bruce again.
"I'm not with Lamar in LA. I can't stop him from calling everyone's phone," Khloe said. She later told the show's cameras, "I know it looks weird – I don't know what to say."
For more on Khloe and Lamar, pick up the new issue of Life & Style, on stands now.