Scott Disick's heart still beats for the "love of his life," ex-girlfriend Kourtney Kardashian.

In a sneak peek clip from an all-new episode of Keeping Up With the Kardashians, the 33-year-old reality star can't help himself from gushing over the mother of his three children.

WATCH: Kourtney Kardashian Criticized for Sharing Photos of Her Children on Hood of $122,000 Car

In the clip, Khloe and Kim Kardashian grill Scott on the status of his on-again, off-again relationship with their older sister after the two took a trip to Mexico together.

Khloe starts egging Scott on by saying, "Get any tickling down there? Like, when you and Kourt kiss, 'cause you know you want it to work…"

"We didn't kiss," Scott says, before Khloe calls him out, reminding him, "You told me you kissed … and you said she didn't kiss you back."

"I kissed her goodnight," he clarifies. "She didn't kiss me back when we were together."

"I'm still turned on by her," he adds, telling Khloe he and Kourtney are not currently seeing anybody else at the moment. "I mean, I technically could I guess. But I just don't feel comfortable."

WATCH: Scott Disick Tells Khloe Kardashian He and Kourtney 'Kissed'

And when Kim and Khloe ask Scott if he's "getting over Kourtney," he said that's never going to happen.

"It's tough sometimes. I feel like I would never be over her," he explains. "She's the love of my life, but I try to do everything to be there for her and there's literally no appreciation for anything ever."

The clip then cuts to a solo interview of Scott who exclaims, "I just hope that one day she understands that I would never wanna be with anybody but her."

ET previously reported that Kourtney and Scott are not together, but keep a close relationship for their kids, sons Mason, 7, and Reign, 2, and daughter Penelope, 4.

As we patiently wait for the next episode of Keeping Up With the Kardashians to air Sunday at 9 p.m. ET on E!, press play on the video below to watch Kourtney confront Scott during the season 13 premiere.

WATCH: 'KUWTK' Season 13 Premiere: Kourtney Kardashian Confronts Scott Disick