It's over for Scott Disick and Kourtney Kardashian, PEOPLE has learned.
Kardashian, 36, and Disick, 32, shared nine years and three children together – though their relationship was frequently strained by Disick's substance abuse issues, including a stint in rehab earlier this year.
Most recently, Disick made headlines when he was spotted cozying up to stylist Chloe Bartoli during a vacation in Monte Carlo last week.
Multiple sources told PEOPLE Disick had fallen off the wagon once again: "He's in a classic shame spiral right now. He knows he's screwing up, and he knows what he needs to do," a source close to Disick told PEOPLE this weekend. "He has people telling him to go home and work things out, to stop this behavior, to repent and to move forward. But he's not doing it."
The photographs that seem to have been the final straw featured Disick touching 25-year-old stylist Bartoli's back as they lounged near a pool. On Friday, the reality star was photographed holding a beer as he spent time aboard a luxury yacht with Bartoli and a group of friends.
"He's operating out of fear and shame right now. He's not seeing things clearly," the Disick source added.
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Disick's struggle with sobriety was a prominent topic on the most recently season of Keeping Up with the Kardashians, which also featured the birth of the couple's third child, Reign Aston, in December. (They also have a son, Mason, 5½, and a daughter, Penelope, 3 this week.)
"I definitely go in and out of happy and dark places in my life, and I wish that I could be a little more consistent, and I wish it was a little bit easier for me to be under control, but it's not," Disick said during a May episode of KUWTK.
Kardashian stepped out on her own in Van Nuys, California, on Friday and, according to PEOPLE's source, had been out of communication with Disick for some time.
Reporting by AILI NAHAS