How about a default option to grant automatic rematch permissions
Option #1. with a win or a loss, the rematch is automatically offered with a switch of sides; if both sides have selected this option, it makes the rematch automatically
Option #2. the rematch can limited to only wins or losses
Option #3. Rematches can be limited to a tiebreaker 3rd game
Option #4. Rematches can be offered with a switch of sides after every game played, with the cancellation of that option available at any time during the game with an prominent link, just like with messages and claim draws etc
Option #5. These could all be specifically selected without being defaults, as preferred