The 58-year-old showbiz matriarch is thrilled the couple - who already have kids Mason, four, and Penelope, 23 months - are expecting their third child together but, as they have been together for eight years, she doesn't understand why they haven't tied the knot yet.
A source told MailOnline: ''Committing to parent three kids, when you haven't even committed to each other doesn't cut it in Kris' book. She comes from a time when, if a girl got pregnant and was still single, she got married as soon as possible.
''And although she understands times have changed, she still has religious values and feels it's only right that Scott make an 'honest woman' out of her little girl.''
It has previously been believed that Scott is more open to marriage than the 'Keeping Up with the Kardashians' star, but the insider says the tables have now turned.
The source added: ''Up until now Kourtney hasn't been interested in getting married, but at 35, she's beginning to feel it's time. She's expecting the couple's third child and if Scott would agree to a small, quiet ceremony - nothing like the one Kim just had - I think she'd be up for it.
''But suddenly Scott is saying, 'Why fix it if it's not broken,' so the subject of marriage once again seems at a standstill.
''Kris on the other hand fears the old adage still rings true; why buy the cow when you can get the milk for free?' And she says if Kourtney doesn't stand up to Scott and insist on a wedding, she'll end up a lonely 40-year-old woman with three kids and no husband.''