The Unbearable Lightness of Being
How we cite our quotes:
When she had been at it for almost an hour, she suddenly said, "What would you say to some nude shots?"
"Nude shots?" Sabina laughed.
"Yes," said Tereza, repeating her proposal more boldly, "nude shots." (2.21.6)
We know that nudity represents humiliation to Tereza. By asking Sabina to take off her clothes, Tereza asserts power over her. But Tereza ends up taking off her own clothes and allowing Sabina to photograph her naked. We can explain this if we go back a few pages to Kundera's description of vertigo, the desire to fall. Tereza possesses a secret desire to be humiliated in just this way.
He often stopped in for a visit, but only as a friend, never as a lover. If he made love to her in her Geneva studio, he would be going from one woman to the other, from wife to mistress and back in a single day, and because in Geneva husband and wife sleep together in the French style, in the same bed, he would be going from the bed of one woman to the bed of another in the space of several hours. And that, he felt, would humiliate both mistress and wife and, in the end, himself as well. (3.1.2)
It's interesting that Franz, like Tomas, has his own set of rules and ideas of what is just, despite the fact that they're both cheating on their wives. Both men are fully convinced that, if the obey their own set of rules, what they are doing isn't wrong.
She was a modest girl and not particularly pretty, but she admired Franz in the way Franz had only recently admired Sabina. He did not find it unpleasant. (3.9.21)
There really seem to be no equal sexual relationships in this novel. One person always has the upper hand.