What does Winston's dream, with the girl with dark hair, mean?

The dream of
the dark-haired girl in the Golden Country who rips off her clothes with a defiant gesture
represents forhis desire to defiantly rip away his own pretense of conformity to the Party. He
feels no sexual desire for the woman in the dream. Instead, he experiences intense pleasure at
her gesture in becoming naked:

With its grace and
carelessness it seemed to annihilate a whole culture, a whole system of thought, as though Big
Brother and the Party and the Thought Police could all be swept into nothingness by a single
splendid movement of the arm.

As we know, Winston wants
very much to rebel against the system that oppresses him. He has started the process through
buying the diary and actually writing in it, an act he knows will probably lead to the death
penalty. The dream of the woman is a continuation of his thought crimes.

Interestingly, too, the dream very closely mirrors reality when he secretly meets
withfor the first time out in nature after they both listen spellbound to the song of a
thrush:

And, yes! it was almost as in his dream. Almost as
swiftly as he had imagined it, she had torn her clothes off, and when she flung them aside it
was with that same magnificent gesture by which a whole civilization seemed to be
annihilated.

It is no wonder that Winston falls in love
with this woman. She is almost literally his dream come true.