Without thinking, Odette asks Swann to post a letter for her addressed to Forcheville. Swann's jealousy gets the better of him and, holding the envelope to the light, he discovers that Odette had spent the previous evening with Forcheville. He is incensed, but reflecting on Odette's tone in the letter, Swann decides that her old letters to him were much more affectionate. His jealousy now has "something to feed on" and begins to take on a life of its own, fixating on the hour of the day that Odette spent with Forcheville. Odette's tacit rejection of Swann stems in part from the Verdurins, who begin to push Swann out of their social circle and especially away from Odette, whom they are trying to fix up with Forcheville. Swann's heart breaks when the Verdurins tactlessly mention, in front of him, a large outing and dinner party to which he is conspicuously not invited.
Swann becomes enraged and begins to see the Verdurins for what they really are. Fuming to himself, he calls Madame Verdurin a "procuress" and denounces her for pimping Odette to Forcheville. He declares to himself that it is "high time that I stopped condescending to promiscuous intercourse with such infamy, such dung," even though, a few hours earlier, he would have laid down his life for either of the Verdurins. Later that night he blasts Odette for not refining her tastes during their relationship, and for not learning how to say "no" to the Verdurins. He begs her not to go see a trashy play with them that evening and threatens to think less of her if she does go. Odette does not quite understand what Swann is trying to tell her and runs off, explaining that she will be late for the overture.
Swann nevertheless continues to love Odette and his obsession begins to warp his perception of time. He compares their relationship to a railway schedule that mercilessly divides up their time together. It is only when Odette displays an unexpected kindness toward him that he suddenly realizes that they are sharing a "real hour" of her life and not just some "artificial hour" that has been invented for "his special use." He has grown so used to jealousy that he begins to see their time together as separate and distinct from the parts of Odette's life that she spends with other people--those parts which really matter to her. When Odette asks Swann to stay a little longer than usual one night and gives him something to drink, all he can think of is Forcheville sitting in the same chair and drinking from the same glass in Odette's "real world."
One day Odette sends Swann a letter asking if she can take the Verdurins to a Wagner concert that Swann has organized. She claims that she wants to do something for them, but also hints that Swann will not be desired company. Swann is so outraged that he swears off Odette for good. Within a few days, however, he cannot help but think of the "other" Odette and "through the chemical action" of his jealousy, he soon feels tenderness and pity for her. His love for her has so far outgrown physical desire that Odette's appearance has become a detached externality that he considers irrelevant. Even when Swann tries to think of Odette as "ugly," his love remains strong, since it has become so intertwined with his daily habits and actions that even death would be unable to strip it from him: "his love was no longer operable," but rather wholly dysfunctional.
Proust uses this section to describe love as primarily the work of one's memory and thus something that never really exists in the present but rather lingers in the past. No matter how much sadistic pleasure Swann gets out of his failed romance with Odette, he is "incapable of inventing his sufferings." Rather, it is his memory of the actual instances of Odette lying to him that define Swann's existence and perpetuate his jealousy. His suffering is thus much more acute since it has nothing to do with his imagination, but is fueled instead by Odette's inability to remain faithful to him. Swann pays dearly for his keen sense of Odette's capacity to deceive him.
The persistence of Swann's love for Odette also depends on the selectivity of his memory. To continue thinking of her as he did when they first met, Swann must purposely ignore and forget the instances that prove Odette's infidelity. When he reads Odette's letter to Forcheville, for example, he ignores the actual meaning of her words and instead conjures up the memory of her old letters to him. Noticing that Odette mentions to Forcheville that he forgot his cigarette case at her house, Swann remembers that when he did the same thing, she wrote to him, "If only you had forgotten your heart! I should never have let you have that back." Since Odette did not add this meaningful postscript to her letter to Forcheville, Swann believes that she loved him more in the past than she loves Forcheville in the present.