Kourtney has really poor social skills.
I used to watch this show during the earlier seasons (2007 up until round 2012). I've noticed over the years that's Kourtney is the most stubborn one out of all 3 girls.
She gets mad easily, she's judgmental, even to Scott, and EVEN when he was trying to work on himself. It's like her has no personality or social skills what's so ever.