Unfortunately, the driving conditions deteriorated and the perfect couple and Santa Claus had an accident. Only one of them survived the accident. The perfect woman survived. She's the only one who really existed in the first place. Everyone knows here is no Santa Claus and there is no such thing as a perfect man.
Women stop reading here, that is the end of the joke.
So, if there is no perfect man and no Santa Claus, the perfect woman must have been driving. This explains why there was a car accident.