This is a convoluted question that can at best result in a convoluted answer. For clarification, was the person charged criminally or is someone seeking protection under the Civil No Contact/Stalking statute? Where in the court proceedings are you?
That is like asking what "reasonable doubt" means. The law, in Illinois at least, does not attempt to define it. The meaning is left to the common sense and understanding of the jury or, in a bench trial, of the trial judge. In my experience, juries and judges in a criminal case take their responsibilities very seriously and are cautious about accepting the testimony of witnesses.
Does that mean they always get it right? Of course not. Bur they do the best they can. There is no other answer to your question.