In Ray Bradbury's Fahrenheit 451, hedonism and narcissism are linked to one of the story's important themes: alienation and loneliness.
Hedonism is "devotion to pleasure as a way of life."
Narcissism is "self-centeredness."
Mildred (Montag's wife) is extremely hedonistic and narcissistic.
Like her waking hours, Mildred's sleep is carefully controlled, just the way she wants it. Like someone dead, she passively rests in bed with sound pumped into her ears all night.
His wife stretched on the bed, uncovered and cold, like a body displayed on the lid of a tomb, her eyes fixed to the ceiling by invisible threads of steel, immovable. And in her ears the little Seashells, the thimble radios tamped tight, and an electronic ocean of sound, of music and talk and music and talk coming in, coming in on the shore of her unsleeping mind.
Mildred is so caught up in experiencing pleasure and being happy that she has become numb to the world, including her husband and things that concern him. One night she mindlessly takes too many sleeping pills, nearly committing suicide. She is unaware that she has overdosed. When Montag tries to tell her, she does not believe him. Mildred has become separated from reality.
When Montag ends up at the house burning at 11 North Elm, he is traumatized that the old woman chooses to stay in her home with her books rather than escape with her life. Montag cannot understand the woman's devotion to books, which are unlawful to own in his society. As he tries to discuss it with Mildred to make some sense of what he has experienced, she has no concern—not for the woman or her husband. Mildred's narcissistic response is about how Montag's reaction to books could affect her.
She's nothing to me; she shouldn't have had books. It was her responsibility, she should have thought of that. I hate her. She's got you going and next thing you know we'll be out, no house, no job, nothing.
Not only has Mildred alienated herself from her free will, but Montag discovers (especially after meeting Clarisse who is so animated and inquisitive) how lonely he really is. When Clarisse asks Montag if he is happy, he unthinkingly says he is. Upon reflection, however, he comes to recognize how far he is separated from the world to which his wife (and most of society) is so devoted. He also comes to recognize his inability to breach the gap that separates him from Mildred.
Montag tries to speak to Mildred about society's view of happiness.
"Happiness is important. Fun is everything. And yet I kept sitting there saying to myself, I'm not happy, I'm not happy."
"I am." Mildred's mouth beamed. "And proud of it."
Mildred is a hedonistic and narcissistic character that takes no part in original thought. She has no desire to know anything of the world beyond how everything relates to her and how good she feels. In her preoccupation with herself, she has distanced herself from reality. She has also turned her back on her husband, making their home a lonely place for him.