Myrtle Wilson, who is Tom Buchanan's mistress in "The Great Gatsby," is described as a thick, stout woman who is in her middle 30s and carries her "surplus flesh sensuously." Her face contains no gleam of beauty, but she has a "perceptible vitality about her as if the nerves of her body were continually smouldering." Myrtle is directly characterized here, but she is also indirectly characterized.
It is obvious to the reader by the description and actions of Myrtle Wilson that she does not care for her husband and feels like part of the upper class when she is with Tom, according to Cliffs Notes. She walks "through her husband as if he were a ghost" as soon as she sees Tom. When she is with Tom, she feels that the lower orders are shiftless, even though she lives in an area of despair, the Valley of Ashes, and is married to a common working man who has no money.
When Myrtle describes her wedding with George Wilson, it is evident that she is not only unhappy but embarrassed by having married a man who had to borrow a suit for their wedding. As soon as she sees Tom on a train, her demeanor improves, as she sees Tom as a way for her to improve her life situation, according to SparkNotes.