"He really does want to be honorable, but the temptations are just too strong," says the source of the 32-year-old father, who spent his weekend making club appearances. (He was photographed kissing a mystery blonde woman in Las Vegas before jetting off to Canada, where he hung out with "cowbabes" at a casino in Calgary.)
"He's acting out because he's in pain, and he's in a spiral," the source continues.
It's been a difficult time for Disick, who lost his mother in November 2013 before his father died just three months later.
Though longtime girlfriend Kourtney Kardashian –, the mother to their three children, Mason, 5, Penelope, 3, and Reign, 7 months – has stayed by his side through the tough times, she dumped Disick last month after he was photographed cozying up to another woman.
"I think Scott doesn't realize how dangerous his partying really is," the source says. "When he's partying, he's distracted. He's not focused on the right things. He says it's his job, but it's voluntary for him. He doesn't need the money. And I don't think he realizes how insidious his behavior really is. And I don't think he gets it. If he did understand it, he'd stop."
For more on Scott and Kourtney, pick up the new issue of PEOPLE, on stands Friday