Why's my girlfriend all of a sudden mean to me?

She is doing things like sending me texts exclaiming she hates me, she calls and hangs up as soon as I answer the phone, she won't talk to me except for when she sees me but just tells me to go away. I'm never mean to her, always give her attention and always tell her I love her or compliment her. Why is she all of a sudden so mean?!?!? Oh her little brother died a few days ago and she's fine and happy and nice around everyone else but me. Why?