Saul's going to kill me. Therefore, my only hope is to leave this place. God didn't tell him to leave. There's no indication of God's leadership in his choice. He simply talked himself into the decision.
Human nature is quite interesting.
We can convince ourselves of just about anything if we really want to. But it's very fascinating to see how we convince ourselves of things we really don't want to believe or desire to happen. We actually find that we manipulate our own actions and eventually the actions of others. Discouragement is a natural part of life. We all experience it at one time or another.