Scott Disick had thought that his ex Kourtney Kardashian and Travis Barker would "eventually break up" before news of their engagement hit, according to reports.

Kourt and Travis announced the happy news earlier this week via Instagram - and, while Scott has stayed pretty tight-lipped on the situation, he apparently thought the pair's relationship would stay "casual".

Discussing Scott's reaction to the update, a source told PEOPLE, "Scott hasn't really wanted to deal with Travis and Kourtney because he didn't feel like he'd have to. At first, it seemed like it was just a casual relationship to him, nothing serious. So he pretty much put that on mute.

"[He] hasn't been giving it too much brainpower, thinking that eventually, they'd break up."

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Revealing more about how Scott is apparently processing Kourtney and Travis' development, the insider added, "But that didn't happen and now he's being forced to deal with it, which is uncomfortable. 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 source continued, saying that Scott was "distancing himself from the family".

"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," they said.

While Scott hasn't publicly spoken out about Kourtney and Travis' engagement, he has now broken his Instagram silence for the first time since the news. Taking to Instagram Stories, he shared a picture of his and Kourtney's youngest son, Reign, 6, with the caption, "after school break down with Reign". Sweet!

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Scott Disick, @letthelordbewithyou//Instagram

Kourtney and Scott have two other children together: Mason, age 11, and Penelope, 9.

We have reached out to Scott's reps for comment.