My fiancé and I sail six months out of the year, usually 75 day rotations. When we are out at sea we never get sick. When we are home together on vacation, he always gets sick first, signs of a common cold, then gets me sick. Every single time we are home together. Before meeting him I would only get sick, a minor common cold, once a year. He says he hasn't gotten sick in over five years. Why is this happening?