Scott Disick Says He Proposed to Kourtney Kardashian, But They 'Got Scared' and 'Never Spoke About It Again'

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On 'Keeping Up With the Kardashians,' the 33-year-old tells Kim and Khloe a huge secret.

The secret's out.

In a new promo for this Sunday's episode of Keeping Up With the Kardashians, Scott Disick, 33, reveals that he actually did propose to Kourtney Kardashian at one point -- with a Lorraine Schwartz ring.

Disick opened up to Kim Kardashian West and Khloé Kardashian while discussing the trip to Aspen, Colorado, he took with Kourtney, 38, and their three kids -- Mason, 7, Penelope, 4, and Reign, 2 -- back in December.

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"Aspen was really good. She usually doesn't want to ever go to dinner with me without the kids, so that seemed like a huge step in the right direction," Disick tells Kim and Khloé of his ex.

"Kourtney and I have been spending a lot more time together, so I decided to take her and the kids to Aspen and she agreed to go. So for me, that's a big thing," he continues. "At the end of the day, it was our first trip I've had in like a long time when we were like actually a family. It got to feel like it was like the old days. I'm happy."

Disick adds that he "hasn't been drinking" and is trying to be "really present" with the family.

"I feel like all Kourtney ever really wanted from me was for me to be sober and healthy and just be there to take care of my family," he tells the sisters. "A year or so ago, I feel like there was a point where we didn’t speak or see each other, so this feels good."

WATCH: Scott Disick Calls Kourtney Kardashian the Love of His Life, Khloé Says the Two 'Kissed'

Kim then stops Disick, asking if Kourtney knew about one ring in particular that he'd purchased to propose with. Khloé immediately confuses it with a different ring they had previously found. "This was a really nice, cool Lorraine Schwartz ring, and then he returned it," Kim clarifies.

"I think I, like, asked her to marry me and..." Scott says, telling a surprised Kim that it was indeed with a ring. "It was really weird. I don't think we told anybody actually. It was somewhat cute, and then we just got scared about, like, media and this and that. And we were like, 'Let's just put the ring aside, and we'll talk about it another day.' Never spoke about it again."

Of the on-again-off-again couple, Kim says she is "really happy" to see the pair "in a good place."

The reality star adds, "At the end of the day, if Scott got his sh*t together, do I believe him and Kourtney would be together? Yes."

For more on Disick's rocky past with Kourtney, watch the video below. Keeping Up With the Kardashians airs Sundays at 9 p.m. on E!.