Full of anger

My friend is full of anger and I don't like that I mean she is telling me about many unhappiness things. I know she is now only thinking the negatives and nothing positive, what is the use she is telling me since she is doing nothing about it. She can approach the person to inform about her unhappiness but she decided to say to me which I cannot do anything about it. It is not up to me to do anything because it is none of my business.

I am sure you know about mind your own business.