Carrie is incredibly self-absorbed in SATC2.
For example, in the movie Carrie is a successful freelancer. As such she is free to spend most of her time as she pleases. When not writing books or articles (on her own time now that she no longer seems to have a regular column) she shops, goes to lunch and generally enjoys herself.
In contrast, Big has a regular job where he likely works long hours. He doesn't have the luxury of sleeping in or making his own hours. He wakes up, goes to work and comes home. As anyone who works can tell you, this is exhausting. As a result, when Big comes home, he often prefers to just unwind on the couch.
..... Carrie could not seem to fathom or understand why Big would prefer to… I don’t know.. relax. Never mind that she relaxes all day, she is completely unsympathetic. In one scene, Big expresses that he’s just too tired to attend a movie premier. He tells her that he had a difficult day- that the market dropped dramatically. Carrie, in turn, completely dismisses him. She insists he attend the event which he eventually acquiesces to. It's all good and well that Carrie displays no interest in Big's feelings, but for some reason Big is expected to be emotionally available and attuned to Carrie and her feelings at all times.
Throughout the movie, Carrie complains about how she feels the "sparkle" is leaving their marriage.
But By "Sparkle," Carrie means the magical things we all do in our leisure time when we have the time and energy to do them. One example of the "sparkle" leaving their marriage is when Big comes home with a take-out container. Carrie, you see, prefers to go out to eat and finds it irksome that Big would grab food on the go.
For Carrie, sparkle is may also refer to a time when she didn't always have what she wanted, when she had to work for things. But Carrie no longer has to work, and she no longer knows what it’s like to be tired, only to tire of things, she is in an ennui of dizzying metropolitan over-satiation. And she will never be happy.