A simple way to lead conversations into a dead end is by focusing on the content.
The form is everything you can see and hear beyond the content. It is what helps you to have an idea of how the other person perceives the status of the conversation in that moment. The form is the way the person expresses what she can’t say or doesn’t know how to say. It can’t be heard in the same way as the content can. But you can pay attention to it and discover when the form lets you solve what you haven’t been able to see in the content.