They can't help it. Anger is believing that they are being made to be against themselves, and it should not have been necessary for it to have happened at this time. They believe that not only are they against themselves, but it was caused by their not admitting or expecting to be disappointed at this time. Anger is feeling wrong for not expecting to be wrong. They feel they fooled themselves.
People can seem to be angry at themselves or at another.
They are really angry that they allowed themselves to be mistaken. Sadness is feeling bad about losing something or someone we believe we need for our happiness. To believe in sin is to fundamentally believe that I am against my very self, my very good, my own future. Unhappiness is just a secularized belief in sinfulness, and is the same as believing that we choose what we know to be wrong or bad for us. Like Adam and Eve we believe we know that some of what we are happy to choose is actually bad for our happiness.