Kourtney Kardashian and Scott Disick have ''never dealt'' with their ''underlying issues.''

The 36-year-old reality TV star recently ended her relationship with her boyfriend of nine years after images surfaced of his canoodling with ex-girlfriend Chloe Bartoli in the South of France, but the couple had been arguing about Scott's partying for months.

A source close to the duo said: ''They've always had problems.

''He would screw up, then apologise, and Kourtney would always make him pay for a couple weeks. Then things would go back to the way they were. They never dealt with the underlying issues. Scott gets freaked out by confrontation; he never dealt with his real problems.''

Kourtney was shocked when she saw the pictures of him with stylist Chloe because she thought he was taking some time away to think.

The insider told People magazine: ''It was the last straw. He was supposed to be taking some time to process things, presumably with the endgame of fixing their relationship. This bottom line is, Scott threw it all away.''

The brunette beauty decided to end their relationship for the sake of their three children, Mason, five, Penelope, three, and Reign, six months.

The source said: ''Her children are her first priority. She was willing to sacrifice her relationship to keep them safe.''