Yes, it wasn't the cancer. She had a show about overprotective mothers and how they sap the spirit of their daughters. So Kate felt ambushed.
They changed so much from the book. Kate and Johnny had a really good marriage in the book. There was no brother named Sean who was gay and wrestling with it. Tully didn't get pregnant and doesn't propose to the father, a younger guy. Kate's parents seem to have a good marriage. Kate and Johnny also have twin boys. Kate and Mara have a contentious relationship when Mara is in her teens, and Mara worships Tully, which strains Kate and Tully's friend