George tries to convince Lennie that Curley's wife is "poison" and "jailbait." George equates her with the girl in Weed and fears that she will interpret Lennie's inevitable petting as a prelude to rape. In George's alarmist reactions, Steinbeck shows how men blame women (even preemptively) for the crimes of other men, the way generations have vilified Eve as a provocateur and the emblem of Original Sin.
Lennie is not attracted to Curley's wife, per se, but to her accoutrements. He doesn't see her as another man's possession (as the other ranch-hands do) but as a tactile privation. Even though she confesses to Lennie her dream of leaving Curley to become an actress, he cannot possibly fill the role of confidante. But with Lennie, Steinbeck personifies the subconscious, animal instincts of man--who would kill a vixen rather than see her continue to tempt and be protected.
In Of Mice and Men, George and Lennie have completely different reactions to Curley's wife. While George calls her a "tramp," Lennie's says, "She's purty." George immediately senses the danger Curley's wife presents and commands Lennie to stay away from her. He is vehement with this telling Lennie, "Don't you even look at that bitch ... I never seen no piece of jail bait worse than her."
Lennie, despite his instant attraction to her (George says, "[W]hen she was standin' in the doorway showin' her legs, you wasn't lookin' the other way, neither."], also recognizes the danger of the situation and begs George to leave the ranch saying, "It's mean here."
In fact, Curley's wife leads to all of the trouble Lennie has on the ranch. It's her fault Curley enters the bunkhouse when Lennie crushes the small man's hand. And it's her who tells Lennie to feel her soft hair, which eventually leads to Lennie snapping her neck on accident.