She's singing about how her man is stepping out on her with another woman, and she's asking him what does this other woman have that she doesn't, and how it's too much pain to bear to have a man that she has to share, and how they don't have to live like that, if only he would stay with her. She can't take it anymore, but by the end of song, even though it hurts her to her soul, she tells him that I can't do this anymore and she knows that if he can't stay she must go.