He couldn't keep doing this to you, yes, it was a dare but you are his girlfriend, he loves you too much to keep it going

you were crying after he yelled at you after all, you hated yelling and he knew it, he had the urge to hug you and comfort you but a dare is a dare

he had to mistreat you for a whole day, that was his dare, his heart was breaking into pieces seeing your tears but he couldn't do anything about it