If you're looking for a more modern take or a detailed breakdown of these themes, you can check out features from these outlets:
: Samantha has an affair with a married man, but the situation takes a turn when his wife catches them and, surprisingly, wants to join in. [S1E8] Three's a Crowd
: The Girls Rewatch podcast features an episode with guest Claire Parker that discusses the "DUFF treatment" of Miranda and the "4th wave feminism" aspects of the episode's plotlines. If you're looking for a more modern take
: Carrie's anxiety peaks when she discovers Mr. Big was previously married. After meeting his "perfect" ex-wife, Barbara, Carrie becomes obsessed with whether she can compete with his past and whether Big is capable of another serious commitment. Big was previously married
: Charlotte finds herself in a dilemma when she dates a man who wants to bring a third person into the bedroom. This challenges her more traditional views on romance and intimacy.