Despite his 15-year age gap with girlfriend Sofia Richie, a source tells PEOPLE Kourtney Kardashian is "happy" her ex is "doing better"

So far, Kourtney Kardashian has remained mum about her ex Scott Disick‘s relationship with Sofia Richie, who is 15 years his junior — but now, a source tells PEOPLE the pairing definitely raised eyebrows within the famous family.

“The initial reaction from Kourtney when she found out that Scott was dating Sofia was not positive,” says the insider. “Like most people, she thinks Sofia is way too young for him and doesn’t get it.”

But Kardashian, 38 — who is dating 24-year-old Younes Bendjima — has since realized that Disick, 34, is “doing so much better” with 19-year-old Richie in his life, the source says.

“He has very much shaped up in the past few months,” the source says. “Kourtney is happy Scott is doing better. Things between Kourtney and Scott are civil.”

From left: Kourtney Kardashian, Scott Disick, Sofia Richie
| Credit: Paul Archuleta/FilmMagic; Mat Hayward/Getty Images; Matteo Prandoni/BFA/REX/Shutterstock

The source says Kardashian, who shares three kids with Disick — sons Reign 3, and Mason, 8, and daughter Penelope, 5 — found out “early on” that her ex had moved on with Richie but didn’t expect the fling to last. (Disick and Richie, who is also a family friend of the Kardashian-Jenners, have been officially dating since September after initially sparking romance rumors in May.)

“Kourtney didn’t think it would last and she never thought Sofia was going to meet her kids,” says the source. “But now, Sofia spends a lot of time at Scott’s, so Kourtney allowed her to meet the kids. She has met them a few times.”

“For a while, the kids didn’t see their dad on a regular basis,” the source adds. “It was very sad, because they missed Scott. Now, he sees his kids every week.”

RELATED VIDEO: Kendall Jenner Shades Scott Disick and Girlfriend Sofia Richie on Instagram

On Sunday’s episode of Keeping Up with the Kardashians, Disick briefly addressed his relationship with Richie — but refused to go into detail.

“Whatever makes him happy — I don’t judge, I don’t care,” Kim Kardashian West said. “I think it’s a good thing. I just hope that he’s making good choices and having fun and that nothing is getting crazy. … I mean, it’s not like we can keep tabs on him forever. He’s got to live his life. Kourtney’s moved on, Scott’s eventually going to move on. If it ends up turning into something, great.”

After being confronted by Kardashian’s mom Kris Jenner about the romance, a visibly uncomfortable Disick did his best to avoid the topic.

“Kris really is like my mom to me … but I don’t really feel comfortable talking to her about my personal or dating life,” he said later. “Truthfully, as much as I’d like to be honest with her and tell her how I’m how I’m really feeling, I also do want to respect Kourtney and her feelings. Maybe down the line, but right now, my biggest thing is just being respectful of everybody.”