The 34-year-old club promoter said while speaking to Kardashian's sister Kim Kardashian in a preview for Sunday's episode of "Keeping Up with the Kardashians" that he hasn't had "fulfilling" relationships since his 2015 breakup with Kourtney.
"She was on vacation with one man the whole trip," Disick said of Kardashian's trip to Cannes, France, with boyfriend Younes Bendjima in May.
"That looks like a happier scenario than me jumping around trying to find happiness and these girls are not fulfilling that," he confessed. "I'm just not happy with anybody."
Disick was in Cannes at the same time as Kourtney, and made headlines for his PDA with 20-year-old actress Bella Thorne.
He confessed Kourtney moving on romantically makes him fear he will be replaced in the Kardashians' lives.
"Sometimes I just feel kind of insecure, 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,'" the star said. "It's a scary thing for me."
Disick, who shares 7-year-old son Mason, 5-year-old daughter Penelope and 2-year-old son Reign with Kourtney, has since been linked to 19-year-old model Sofia Richie.
The pair were affectionate during a trip to Mexico in October.
"Scott and Sofia seem very happy together," a source told E! News at the time. "They always had their arms wrapped around each other and were kissing and hugging."
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