I think it's quite sad if people become emotionally attached to a tennis player or any other individual sportsman. They couldn't care less about anyone but themselves. At the end of it all they are in it to make money, win or lose none of that is coming your way, so why get upset or feel elated if a player loses or wins, just watch the sport and enjoy the contest between two players.
Being emotional/passionate about a sporting club is a totally different matter, that is perfectly understable, it's a collective effort. Players, coach, club staff, fans etc
Whenever there is any doubt, there is no doubt.