Why is my girlfriend so mad at me?

Okay well my girlfriend's dad died like a week ago and I thought she would be over it by now but she has been acting all emo and stuff and it was annoying me so much and I got mad and slapped her. Now she's all angry at me and stuff. Why? I was just trying to make her get over her dad's death and move on. It was just tome though love. So why is she mad at me?