Benefit of the Doubt

For a peaceful mind, always give people the benefit of the doubt. But for your own good, after repetitions of action, you have to limit it until your doubts are cut down into just two. 

The first one is that maybe the person is doing bad things intentionally, and the second one is that maybe he is just too stupid to realize that what he's doing is harmful to others despite you reaching out to him about it. 

If things go down to this, it is high time to avoid contact with that person as much as possible so you can continue to enjoy your tranquility and safety.