Curley’s wife is alienated because she married a pompous idiot who keeps her on his ranch, lording her beauty over the other men. She has no friends, and she is completely isolated.
Curley’s wife does not even have a name of her own. She is a new wife, and the men say that “Curley is cockier'n ever since he got married” (ch 2, p. 13). She is always objectified, described as a flirt and a “looloo” and she’s got the eye.
She ain't concealin' nothing. I never seen nobody like her. She got the eye goin' all the time on everybody. I bet she even gives the stable buck the eye. I don't know what the hell she wants. (ch 3, p. 25)
George immediately calls her a “tramp” when he first finds out about her, and believes she is trouble. He tells Lennie to keep away from her.
Curley’s wife is ridiculed and treated as nothing more than a sexual object, but she has dreams. She tells them that she could have been “in shows” and I guy told her he could put her in movies (ch 4, p. 38). Instead, she has no one.
"-Sat'iday night. Ever'body out doin' som'pin'. Ever'body! An' what am I doin'? Standin' here talkin' to a bunch of bindle stiffs… an' likin' it because they ain't nobody else." (ch 4, p. 38)
Curley’s wife calls the men “bindle bums” and gets frustrated because they don’t tell her things. This only increases her alienation, because on the one hand she feels she is better than them, while on the other hand they won’t treat her like she means anything.
All page numbers from: http://staff.oswego.org/ephaneuf/web/ENG_9R/Steinbeck,%20John%20-%20Of%20Mice%20and%20Men.pdf