How am I supposed to deal with her..?

Women are not one to talk about what is worrying them especially if it concerns the relationship or if they doubting anything. If you ask a lady once what is wrong and she says nothing, take it from me leave it at that. Yes we are emotional and might turn around and say that you do not care but we get frustrated that after we say nothing, you keep whats wrong. Give her time to get her strength to talk to you about it or she would rather not mention it you. Thats just how we are. Unfortunately its not easy for us to speak about things that worry or hurt us. Just be patient with her. Women are not an easy species to deal with me i know i am female myself. All the best :-)

Dont ask her about the problem or the that has made her mad,Dont mention that at all,try to distract her with something else,tell her something else maybe a story,try to make her calm,she will talk about it when she becomes ready,dont push her to do it ASAP.

Leave her alone when she is mad. Some people do not want to share their problems. Give her space.

Give her space let her calm down then ask what's wrong

HER WHO ? YOUR MOM ? SISTER? GIRLFRIEND, WIFE, BEST FRIEND ,TEACHER, DOCTOR ? who it really makes a difference.