For all of Rhoda's loathing of Charlie, Valerie Harper and Richard Schaal were actually married, 1964-1978.
The title refers to the award given to the most outstanding person in a field by presenting him with a "Man of the Year" award. The most famous is the Man of the Year award presented by Time Magazine for the person who most affected the news events of that year. Since the 1990s they have changed the award to the Person of the Year.