The entirety of "Autumn Sonata" builds to a devastating, all-night confrontation between Eva and Charlotte. After a nightmare, Charlotte is comforted by Eva, but this moment of tenderness quickly unravels into a brutal airing of grievances. Eva accuses Charlotte of a lifetime of sins: forcing her to have an abortion as a teenager, controlling her appearance, being absent for her son's life and death, and ultimately causing Helena's debilitating illness through emotional neglect.
Charlotte's defenses crumble, and she reveals that her own parents were cold and never touched her, leaving her incapable of showing love. She confesses her own helplessness and begs for forgiveness. The climax of the confrontation is Helena dragging herself from her room, crying out for her mother, a visceral manifestation of the pain being discussed. The next morning, Charlotte flees. She gets on a train with her agent, complaining about the ordeal and callously asking, "Why couldn't [Helena] die?" This reveals the profound depth of her self-absorption and suggests any remorse she showed was fleeting. Eva, meanwhile, visits her son's grave, contemplating suicide, before returning home wracked with guilt for having driven her mother away.
The film's final twist is one of perspective. After such a brutal and seemingly final severing of ties, Eva writes a letter to Charlotte. In it, she apologizes and expresses a desperate hope for reconciliation, stating, "It must not be too late." Viktor reads the letter aloud, and his voice blends with Eva's. The film ends with Viktor sealing the envelope, its delivery and reception left entirely uncertain. This ending reveals that despite the catharsis of expressing her rage, Eva is still fundamentally trapped in a cycle of longing for her mother's love, making the film's ultimate conclusion deeply tragic and ambiguous.