Jennifer Lopez might know something about this.
I do think Big thought Natasha was "wife" material. His first wife also seemed like Natasha. When Carrie and her friends had lunch and they were talking about The Way They Were I think there was a lot of truth there. However when Carrie thought complicated I thought drama. She always wanted her and Big to be farther along than they were. Or more than they were. I can see where Big just wanted someone who was easier.