Why did Curley's wife become upset after Lennie says "If George sees me talkin' to you he'll give me hell," ?

Curley's wife is lonely and desperate for company. She feels so isolated that Steinbeck does not even give her a name: she is simply known as Curley's property. Curley's wife lives on a ranch full of men who do not speak to her because they do not want to get fired. Lennie does not understand the intricacies of speaking to Curley's wife: he just knows George told him not to. Curley's wife is frustrated because she knows she is close to talking with somebody. She vents her frustrations to Lennie.