Being around a person that's mad all the time

She's mad at her man but treats me like crap! I've never done her wrong! But she acts like I'm her enemy! I love her to death and I see her a my own! We work together and I try to stay happy and cheerful but she's always negative with me! Like she don't want me here when I haven't done any wrong to her! The stress of it is driving me crazy! I can't seem to do anything right with her!