In chapter two, George and Lennie learn that Curley has gotten married two weeks ago:
"Seems to me like he's worse lately," said the swamper. "He got married a couple of weeks ago."
We also learn that this has made him "cockier."
From the start, Curley's wife is linked to Curley's aggressive stance towards the much larger Lennie. Even before the characters meet, she is a symbol of the danger Lennie faces on the ranch.
Curley wants to prove his manhood in front of his new wife, which means taking on and beating larger men in boxing matches. At the same time, from the first time he lays eyes on her in the bunkhouse in chapter two, Lennie is innocently attracted to her. His eyes run over her as she stands in the light in the doorway with her banana curls, rouge, red-painted fingernails, and red backless sandals: "Lennie watched her, fascinated."
We're not sure how old Curley's wife is, except that she is at least fifteen, but she seems to be very young; she wishes she could go to Hollywood and be in the movies. Although she comes across as hard with her brittle voice and flashy clothes and makeup, she is also largely innocent and out of place on the ranch, just like Lennie.
Even if Curley was not such an insecure, bullying man, his wife's presence on the ranch meant trouble for Lennie. To him, she seems like a shiny toy he can't help but want to touch.