Yep, as NitrogenSports said, terms and conditions say that when there is a retired player on a match that is in your single bet, parlay, whatever, the result will depend on the match official's verdict and is usually pretty obvious.

This case reminds me of once there was a guy complaining about the opposite - he had a tennis match i believe as well, and he bet on the guy that was declared the winner when the opponent retired. However the bet was shown as cancelled.

So if you bet on the other guy and the bet showed as cancelled, how would you feel? Exactly. Sportsbooks have their own rules that are followed no matter the result, to ensure the fairness is even throughout all bets.

Take the L man, it's just bad luck. Can't blame it on the house.