@Netaporter I think the interesting dynamic is between Carrie and Miranda - in AJLT S1 Carrie did exactly what Miranda did in the last episode and probed what Miranda was up to with her relationship with Steve/Che and Miranda immediately became defensive. Miranda can't be surprised that Carrie is doing the same, surely? It was Miranda who got Big to come to brunch that time before sending him to collect Carrie from Paris wasn't it? She can't have forgotten that she knows her really well?
Are you thinking of when Che and Miranda did the deed in Carrie's kitchen while she peed the bed post operation?
I think it's really interesting to compare those two situations. Carrie was really angry, and it was very much the selfish Carrie type of anger about he needs not being met (even if it had justification this time). Miranda was a bit drunk and pretty much "taken" by the much more dominant Che. She was exploring some newly awoken sexuality, vulnerable, confused, excited and a bit pissed. She tried to make light of it when Carrie was angry about the pee incident. Carrie was pretty withering when she asked Miranda what she was doing, leading a chastened Miranda to break down and cry about how unhappy she was with Steve. And she was also angry and defensive, but also properly distressed and I thought a bit scared - of what was happening in her life or of Carrie's disapproval I am not sure.
Miranda's comment to Carrie was light hearted and actually seemed supportive of the flirtation she was witnessing between her and Duncan. No judgement, more curiosity. Nothing Carrie of old wouldn't have said around the breakfast table to one of the others. And Carrie flew off the handle with a completely over the top reaction, turning her - guilt? anger? frustration? - onto Miranda so she ends up begging not to be iced out of her friendship. Not to mention her utterly ridiculous claim about her 20 year history with Aiden (2 years tops, Carrie), and completely forgetting her own rule that she doesn't have to stay faithful. So I think she was angry about being caught out, and she hasn't really talked at all to her friends about what's going on with Aiden - just vagaries - because she doesn't know herself what she's doing with him, but can't accept his life is not for her. And actually Duncan - sophisticated, feted writer, a grown up Berger if you will, is much more her bag.
Also remember her little spat with Anthony in a previous episode, who was actually protecting her in asking what the 5 year deal was all about and voicing his disapproval? He also ended up begging Carrie not to drop him. Which lady bountiful agreed to, but with barely a smile. She's become quite monstrous.