Deceitfulness

What do you do, when you believe that you haven't done anything to cause someone to mistrust you, but you sense or almost know that the mistrust is there? They haven't said anything to you, in fact, they put on this facade like they do trust you, but you know within your heart that it is a facade. Little things done, little things said, with big meanings (actions speak louder than words). How do you handle someone who secretly has dragged your name down, but openly acts like they haven't done anything, like everything is copastatic. Do you go to them and ask them? Do you just pray for them? Do you allow yourself to get so frustrated that you begin to treat them in a mean way and allow your blood pressure to rise? Or, do you just keep going on being nice to them and hope something will bring it to light?