Scott Disick and Kourtney Kardashian split up in 2015 following nine years together.
But partygoer Scott – who has since moved on with Sofia Richie – is still “insanely jealous” of his ex-girlfriend’s hunky toyboy lover.
The mum of three, 38, and former boxer Younes, 24, first went public with their romance in May of last year during a trip to Cannes after meeting the previous October.
And the loved-up pair have been going from strength to strength ever since – despite many saying it wouldn’t last because of their age gap.
“Scott is still insanely jealous of Younes,” a source told E! News . “He just can’t come to terms with the fact that Kourtney has found true happiness with someone else.”
The source went on: “Scott is hurt she chose someone else and it really bothers him.
“He can’t control his emotions about it and lets it all out.”
“It makes things between them tense and unpredictable,” the source added.
“Kourtney never knows when he is going to fly off the handle or go nuts about something. Scott just never thought it would last this long with Younes or become so serious. Nobody really did.”
After finally going public with their relationship last summer, Kourtney hasn’t been afraid to flaunt her and Younes’ romance on social media as they gallavant around the globe together.
The pair most recently enjoyed a sun-drenched trip to Mexico and last month Kourt shared a romantic snap of them “dancing by the moon” at home in Los Angeles.