What happened to the man i fell for

Another day has ended. He sets a mere few meters away but not a word to me. Its funny, how you can fall for someone and they walk away without even a glance and don’t even bother to say goodbye. The immaturity astounds me. Is it mental illness, is it mere immaturity? Surely people can’t behave this way on purpose. I’m sad for what I fell for, that its come to this. I’m ready to move on. How to tell him.