There is no obligation on the part of anyone to offer or accept a rematch, much less a third game. So, "fair" is not relevant in this context, IMHO.
Challenges

true but i accepted his rematch after i beat him the first time. It was kind of disappointing when i went for a best of 3 to see he doesn't accept certain invites
so I beat a player, he challenges me. he beats me the 2nd time around, so I go to challenge him but he only accepts players above a certain level......... is this "fair"?