The character of the woman in the hotel room with Willy Loman is not developed in the drama. She functions as a minor character, but her very presence is of vital importance. Biff's finding Willy in the hotel room with this strange woman forever alters his opinion of his father, drives an unspoken wedge between them, and sends Biff spiraling into an adult life of failure and personal destruction.
Biff and Willy never discuss the incident, but it poisons their relationship. Biff's pain and disillusionment fester as an intense anger and sense of betrayal; Willy spends years struggling to rationalize all the actions of his life. The woman in the hotel room participates in the inciting incident that sets events in motion leading to the tragic conclusion of the play.