Xi Nan's exclamation had a particularly different, comical effect given the situation.
Gu Xiaonuan originally felt sympathy for the deaf-mute girl being auctioned off to a group of lecherous old men downstairs, but after hearing Xi Nan's comment and considering that she was there voluntarily, her sympathy for the girl suddenly waned considerably.
From birth, one must face choices, unceasing choices, constant choices, which then shape their current circumstances.
Gu Xiaonuan couldn't interfere with someone else's life and choices, and besides, who's to say that the deaf-mute girl wasn't there by her own decision?
When Gu Xiaonuan chose to marry Si Yuchen, she had thought at the time that she would surely regret it one day.
Now, she felt some regret. But the choice had been made, and it was a sign of weakness to even mention regret to herself. No one would sympathize because these were all personal choices.