Tereza remembers the fantasy Sabina outlined to Tomas in the letter she discovered (in which Sabina and Tomas make love on a stage). Tereza is now excited by the thought and repeats Sabina's words to Tomas while they make love.
She considers that, if Tomas took her along on his affairs, she would no longer feel betrayed.
She and Tomas would be one, and other women would merely be their playthings.