Dear thissucks:
If I understand correctly, he believed for a while that he caught the virus from you. Then he found out that he didn’t. Maybe he got very scared and since his scare, even though he was not infected, he associates you with the fear he experienced intensely. If this is so, fear is a strong motivational force keeping people away from perceived danger. If this is the case, I think you are wasting your time with him.
anita