Was Sadie different?

Just watching the movie now (my 100th time it feels like haha) and when Country-Sadie bumps into City-Sadie's ex husband at the plaza before he asks her out for dinner, he says to her after commenting on her wholesome image and how she handled his son that "It reminded me of a girl I used to know", aiming that comment to her thinking she was City-Sadie.
Does that mean that when he met City-Sadie and fell in love with her that she wasn't always the bitch she turns out to be?

Wish there was more backstory on them!