• Kourtney Kardashian announced her engagement to Travis Barker Sunday
  • Scott Disick needs some time to "make his peace" with the engagement news, a report says
  • Disick reportedly initially thought that the couple's relationship was casual and that they would eventually split

Scott Disick needs some time to process his ex Kourtney Kardashian's engagement to Travis Barker, a report says.

On Sunday, the "Keeping Up With the Kardashians" alum announced her engagement to the Blink-182 drummer, who arranged a romantic beachside proposal in Montecito, California, over the weekend.

While their friends and family have been celebrating the relationship milestone on social media, a source told People that Disick is distancing himself from the Kardashian-Jenner family in order to "make his peace" with the engagement news.

"Scott hasn't really wanted to deal with Travis and Kourtney because he didn't feel like he'd have to," the unnamed insider said. "At first, it seemed like it was just a casual relationship to him, nothing serious. So he pretty much put that on mute. Hasn't been giving it too much brainpower, thinking that eventually, they'd break up."

However, the split he was reportedly expecting didn't happen, and Disick is now "being forced to deal with it, which is uncomfortable," the source added.

"He knows he has to lean into the discomfort and get past it. He understands that it's not Kourtney's job or Travis's job to make him okay with this. It's his job, and if he's going to co-parent with Kourtney, which he has been, he has to process this and make his peace with it," the insider continued.

As a result, Disick reportedly decided to distance himself from the entire family.

Explaining the reality star's decision, the insider told the outlet, "It's not about them, it's not about Kourtney. It's about him needing some time to process this and deal with it on his own, without them. He'll come around soon."

Disick and Kourtney had an on-again, off-again relationship from 2005 to 2015. The exes share three children together — Mason, 11, Penelope, 9, and Reign, 6.

After Kourtney and Barker's engagement made headlines earlier this week, reports surfaced that Disick didn't react well to the news.

One source told E! News that Disick is "still very bitter" about his ex's relationship with the musician despite him wanting her to be happy. The insider claimed that "behind closed doors, [Disick] will always have regrets about their relationship and why it didn't work out. He is bitter because he's never seen Kourtney this serious about someone."

In an episode of "KUWTK" in 2017, two years after Disick and Kourtney parted ways, he admitted his fears of seeing his ex get into a serious relationship with someone else. According to Disick, he was afraid he would lose his place in the family once Kourtney finds a new man and introduces him to the Kardashian-Jenner clan.

"Sometimes, I just feel kind of insecure," Disick told Kourtney's sister, Kim Kardashian, at the time. "Like if Kourtney met somebody, fell in love, got married, and then everyone's like 'Eh. We have a new Scott. Like we don't really need to be close with him anymore.' Even though I get it. We have kids."

Following his split from Kourtney, Disick was linked to a series of models before he began a long-term relationship with Sofia Richie in 2017. The two called it quits last year, and he moved on with model Amelia Gray Hamlin.

Disick and Hamlin parted ways last month.

Scott Disick
Scott Disick is pictured at the Sugar Factory American Brassiere on Oct. 13, 2017 in Bellevue, Washington. Mat Hayward/Getty Images