The following is taken from Shmoop.com.
Curley’s wife has no name and is initially seen as the possession of her husband. She is also a good-looking lady who wears quite a bit of makeup, form-fitting dresses, and ostrich feathered-high heels. As the only woman on the ranch, Curley’s wife is lonely and sad – something her marriage to Curley only makes worse. She reveals throughout the course of the story that she is unhappy in her marriage because her husband seems to care little for her, and is really more interested in talking about himself than anything else. Further, she laments her lost potential; she details twice that she could’ve been a Hollywood movie star, though the chance was taken from her by her mother, who worried she was too young.
But Curley’s wife has another side that is petty, cruel, and almost as self-obsessed as her husband. She flirts deliberately with the ranch hands and causes them to suffer Curley’s hot-headed, glove-wearing wrath. Further, she does little to hide these flirtations from her husband, though they’re likely to infuriate him and make him feel even smaller. Come to think of it, this is probably why she does it at all.
You’re likely to lose all sympathy for this woman as a desperate captive of ranch-living the moment she barges in on Lennie, Crooks, and Candy in Chapter Four. She singles the men out, calling them the weaklings of the pack, left behind for a reason. In her conversation with the men, she reveals her strange dilemma – while she scorns and mocks these ranch men, they’re the only ones she has to talk to, and talk she will, whether they’ll listen or no. Still, in order to make herself feel bigger (especially relative to those who won’t give her the time of day), she has to seek out those who are smaller. She cruelly cuts down Candy for his old age and meekness, Lennie for being “a dum dum,” and most harshly, she threatens Crooks with a lynching.
Finally, Curley’s wife, like Lennie, has no ability to self-evaluate. Unlike Lennie, she doesn’t have the excuse of being mentally slow.
She’s just self-obsessed, and unable to judge herself and her position honestly. It seems at every chance she gets, Curley’s wife likes to talk about her lost opportunities. She speaks of a traveling actor who told her she could join their show, without gathering that this is a pretty standard pick-up line. Same with the offer to go to Hollywood: Curley’s wife has convinced herself that her mother stole the letter, rather than realize the men weren’t really interested in her for any actual talent. Curley’s wife’s obsession with herself ultimately leads to her death.
She knows Lennie is supposed to stay away from her, but thrives on his attention and wants his praise for her soft hair. It is not coincidental that she ends up losing her life because she didn’t want Lennie to mess up her hair. This final event sums up Curley’s wife’s role fairly neatly.