Sofia Richie had a "huge issue" with Scott Disick and Kourtney Kardashian.

Sofia Richie

Sofia Richie

The 'Keeping Up With The Kardashians' star discussed the end of his romance to the model on the family's E! reality show and now an insider has claimed Sofia found it difficult seeing her then-flame Scott close with his ex-partner Kourtney, with whom he shares Mason, 11, Penelope, eight, and Reign, six.

A source told E! News: "Sofia and Scott had to navigate many issues together throughout their relationship. It was no secret they had their ups and downs when it came to Kourtney. Once Kourtney and Scott became closer and were spending more time together with the kids, Sofia had a huge issue with it. She thought she was losing him to Kourtney and was jealous at times ...

"Sofia is not surprised that Scott shared their relationship issues with the Kardashian family and publicly on the show. She wished it stayed private but knew it would happen when they split. Sofia has moved on and put the drama behind her. At this point, there is no chance they will ever get back together."

In a recent episode of the E! show, Scott revealed Sofia gave him an "ultimatum".

He told Khloe Kardashian and Kim Kardashian West: "I thought I would give it a try and make her more of a priority, but then even when doing that, she was like, 'I don't wanna share you as a boyfriend with Kourtney.

"Instead of just wanting to work with it, she literally said, with an ultimatum: 'You have to choose, me or Kourtney.' And I was like, but Kourtney is Kourtney and my kids. It's a unit. I said, 'How could you even want that for me?' It just became an impossible relationship to keep carrying on with."