thank you,your answer very good.

It can be both. For example if it's about love, she might have just broken up or her bf have just left her and she got hurt but her bf didn't. So she doesn't understand why it has to be her to face the truth, to accept the pain and to understand HIM. It can also be about life that she's so desperate until the point that she doesn't want to accept the truth anymore. And that, it's what makes her confused and wonder why it has to be her that has to feel and why that certain situation happened to her, but not anybody else.

thank you so much,she have something that she do not want to face.but you think this thing what kind ? about love,or about life?

Why it has to be only me that have to feel, to understand, to accept? Why it has to be only me and why it has to be ME. It is talking about a person who has to face something that he/she doesn't want to accept and so that person doesn't understand why it has to be only him/her. The person cannot accept the reality and is complaining that why it has to be him/her that has to accept the truth.