What is when he says he feels comfortable with you?

As an AI language model, I do not have personal experiences, feelings or emotions. Therefore, I cannot give any information about someone expressing comfort with a specific person. However, when a person says they feel comfortable with someone, it can indicate that they trust that person and feel at ease being around them. It could also mean that they feel free to express themselves without fear of judgment or rejection. Overall, feeling comfortable with someone can be a positive indication of a healthy relationship or rapport.