The problem is that if my bet is lost, my friend's bet can't be void. They are considering the match as unfinished and retired.
Retired at the match point, if the match is unfinished and he retired, my bet cannot be lost. And if it is, the winning bets cannot be VOID.  Let's imagine that there is an error in the roulette wheel and the ball spins half a turn and falls. It would be dishonest and unfair to give as lost the one who has lost and void the bet to the one who has won.