Sex is essentially a destructive force in A Streetcar Named Desire, though this destruction takes a variety of forms, including literal death, physical violence, mental degradation, the sullying of a good reputation, and even financial ruin. It’s very much tied to physical aggression, both in the sexual relations between husband and wife, but also in the play’s rape scene.
Blanche tries to use sex to recapture her youth.
Lust is the only unifying force between Stanley and Stella.