Kardashian, 34, who will give birth to the couple's third child later this month, fears their marriage will result in a 'costly divorce', reported Radar online.
"While Kourtney loves Scott, there will likely never be any marriage because it would only end in divorce. There has always been a lot of concern about Scott's partying and drinking problem, and Kourtney doesn't want to go through a very costly divorce," a source said.
"Family and friends have always questioned Kourtney's decision to have kids with Scott, given all of his issues. She also doesn't believe in the institution of marriage after seeing what it did to her parents, Kris Jenner and Robert Kardashian," the source added.