Curley is not cruel to his young wife, just possessive. From what she confides to Lennie in the barn we can assume that she is still only fifteen or at most sixteen.
"Well, a show come through, an' I met one of the actors. He says I could go with that show. But my ol' lady wouldn' let me. She says because I was on'y fifteen. But the guy says I coulda. If I'd went, I wouldn't be livin' like this, you bet....Well, I wasn't gonna stay no place where I couldn't get nowhere or make something of myself....So I married Curley."
She is too young to be married. She is really not the least bit interested in sex. She has unrealistic fantasies about being in the movies, and her make-up, posturing, and flirtatious behavior are all imitations of actresses she has seen in movies. She is trying out her sex appeal on the workers without any intention of seducing any of them. If anything, Curley has had a negative impact on her attitude about sex. She is a strange, mixed-up young character. She acts sexy but doesn't want anything to do with sex. Curley himself has probably never been able to consummate their marriage. She is continually fleeing from him and hiding because sexual intercourse is not only unpleasant but probably completely impossible for her. The fact that her husband has his hand smeared with Vaseline and covered with a work glove strongly suggests that the girl has s fairly common condition called a "tight hymenal ring" which makes penetration impossible. According to a medical dictionary, this can be corrected by a doctor or by manual dilation. Curley is obviously trying manual dilation. His wife finds all of this painful and disgusting. It is affecting her by giving her a negative attitude towards sex at the same time that she is having fantasies about becoming a sexy movie star like Jean Harlow. Curley is making her unhappy. She must regret ever marrying him--but she wanted to get away from her mother, and now she is a prisoner.
Curley's wife is just a pawn in a larger game. The author John Steinbeck wanted to end his story with George killing Lennie. George has to have a good reason for doing so. Lennie had to do something "bad," as he had done in Weed, and be chased by a lynch mob. Steinbeck decided that Lennie would kill a woman and have to flee. The author created the most likely kind of victim, a young, naive, lonely girl who would get too close to Lennie and arouse him unintentionally, resulting in his killing her accidentally. Curley's wife was created to fit the author's plot needs.
At first, Curley's wife seems to be a little too flirtatious, seemingly intent upon causing a fight between Curley and one of the other ranchers. However, in Chapter 4, she reveals this provocative side in addition to another side of her personality that we might find more sympathetic.
In Chapter 4, Curley's wife reveals to Crooks and Lennie that she visits the workers because she is lonely and bored, being stuck in the house all day and forced to listen to Curley's insistent bragging about himself. As she is leaving them, she admits:
I'm glad you bust up Curley a little bit. He got it comin' to him. Sometimes I'd like to bust him myself.
Curley's wife also claims that she could have been "in pitchers" (an actress in the movies). So, she feels like she got stuck with Curley. In this respect, she has something in common with the other workers. She is stuck, just as they are stuck in a difficult situation. The ranchers are notorious for wasting their money on women and alcohol; they never save enough to find a better life. Curley's wife is stuck with a rude, possibly abusive husband. She probably felt the need to get married so that she could be provided for. She may have a roof over her head, but overall Curley's affect on her (and everyone else really) is largely negative. Not to mention, he objectifies her (to the other men) and thus shows signs of treating her like she's his property.
Yes I do believe that Curley leaves a negative impression on his wife. Firstly he neglects her and her feelings! You will never hear Curley's wife talking about how much Curley spends time with her or asks about her feelings. It's actually the other way a round! The only thing you hear her every talking about his Curley's bravado and her desire to be somewhere else. If he truly loved her I'm pretty sure Curley's wife wouldn't be going around trying to find open ears to listen to her and the attention she's not getting from Curley.