Given that Nora's school friend Cristina's intervention, however unintentionally, lays the seeds the financial if not the emotional destruction of Nora's happy home, it might be best to not read the central theme of "A Doll's House" as the simple need for female liberation. After all, Cristina has worked hard all of her life, and even her marriage was a kind of work, falsely chosen for financial remuneration rather than love. Ironically, Cristina's early hard work and self-sacrifice for her family formed her own happiness in later life as a woman, as she finally marries a man who loves her, while Nora's feminine wiles and deception in pursuit of her husband's health ruins her own domestic bliss.
The difference between Nora and Cristina, however, is deception -- Nora, as indicated by her costumed performance as a sexy Spanish lady who dances the Tarantella, is constantly lying...
Cristina, at least, never lies about her motivations, even when she has married for reasons other than love. Cristina knows who she is -- and Nora does not, because she has always been performing for her father, husband, and children. Nora is a stranger to herself, merely playing at the appearance of being a grown-up who knows what to do in difficult situations. Ultimately, it is truth, rather than falsehood, that must be the basis for the construction of the self -- this is Ibsen's most crucial theme, as is evidenced by the slamming of the door upon Nora's old life, as the girl, now finally a woman, enters into an unknown world, just as she slammed the door on the cold at the beginning of the play, entering a known, but lie-filled room.
