The 39-year-old reality star has three children - Mason, eight, Penelope, five, and Reign, three - with her former partner Scott, and is said to be worried that he might go back to his partying ways in the wake of his recent split from 19-year-old girlfriend Sofia.
A source told People magazine: ''Her concern is that Scott will go back to partying every day and be MIA. Sofia was a good influence on Scott. Since she has been around, he has been drinking less and acting more like an adult.
''The kids are all very happy that Scott is around and Kourtney would hate for that to change.''
Scott previously dated the 'Keeping Up with the Kardashians' star on and off for nine years and was known for vanishing for several days and attending countless parties whenever the pair hit a bump in their relationship.
The news of Scott, 35, and Sofia's split comes just days after Kourtney - who is now in a relationship with Younes Bendjima - was said to be ''on better terms'' with her ex now that they've both seemingly moved on.
A source said: ''Scott and Kourtney are on better terms. He was hung up on Kourtney forever and really wanted to make that relationship work, but he's finally come to terms with the fact that she's moved on.''
The insider at the time explained that thanks to Sofia, Scott hasn't been partying as much as he did when he was single.
They added: ''He's not partying like he was just a year ago and seems to be in a healthier place mentally and physically. Everyone in the family is really happy with how he's doing lately.''
It was also recently claimed that Kourtney ''trusts'' Sofia - who is the daughter of music legend Lionel Richie - with helping to look after her brood.
A source said: ''It helps that Kourtney now trusts Sofia. The kids are allowed to spend time with her. Sofia likes having them and helps Scott. So far, the kids are giving Kourtney good reports about Sofia.
''Sofia has shown over and over again that she is willing to stay with Scott even when things are not great - but Scott is doing well lately. [He] isn't really partying and spends a lot of time with his kids.''
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