What Tohsaka said about the personalities must be true: Emiya never listens to Saber, and heedlessly loiters around alone, just begging to be attacked or be tricked by other masters, and Saber shows the same headstrong disrespect by undertaking the battle Emiya didn't yet want to initiate. They are a perfect match, even though in this case it looks like they are a perfect match for a disaster, not for a success...