In a sneak peek at Sunday's episode, tensions are high as the reality star and her estranged husband Lamar Odom make their way to New York City to attend her brother-in-law Kanye West's Yeezy season 3 fashion show in February – which marked the former NBA star's first public appearance since his near-fatal overdose in October.
"How was therapy today?" Khloé, 31, asks him in the clip, which was filmed as the two flew out of Los Angeles via private plane.
"Good," answers Odom, 36.
Khloé sighs and points out how calm he seems compared to her.
"You're just chilling, right?" she says. "You don't have anxiety, only I do."
As Odom remains silent, reading a newspaper, Khloé addresses the camera in a confessional, explaining that she decided to make the trip with her ex because she thinks "this is something he truly wants to do."
"And at the end of the day, I just want Lamar to be happy," she added. "I still feel a ton of anxiety and pressure, but if this makes him happy and I can keep him safe, then that's a match made in heaven."
RELATED VIDEO: See Lamar Odom's First Public Appearance Since His Near-Fatal Overdose
Khloé's sister Kim Kardashian then phones in via FaceTime and assures the duo that's everything's going to be fine.
"Just relax. I've got the perfect outfit. I got it custom made for you," Kim, 35, tells Odom. "Have fun! Love you, bye!"
But Khloé can't seem to shake her nerves: "I'm nervous, like, this is nerve-racking," she tells Odom. "You haven't been in public, ever. I have more anxiety than you do, I'm sure, but it's because I don't think you understand."
Odom reassures her that he "can understand," but Khloé doesn't seem convinced.
"I know you want to go and I know all that, but it's a lot, that's all I'm saying," she says.
At the time of the trip, a source told PEOPLE Khloé made sure Odom was "taken care of."
"For Lamar, it's very important that he keeps regaining his old life," the source said. "This will motivate him so he is able to keep focusing and work hard. Think of it as a reward. Flying on private jets across the country was his life before. Khloé is nothing but protective of Lamar. She would never jeopardize his health. It's very exciting that Lamar is getting back into his old world. No one deserves it more."
Keeping Up with the Kardashians airs Sundays (9 p.m. ET) on E!