Playing Cards

     When my daughter was growing up one of the things we liked to do was to play card games. Since she rarely played with anyone else, she learned how to play from me. In some cases I did not know the "official rules"; in others I modified them. As an adult when she began to play with her husband, he would sometimes look at something she had done and say, "That's not how you play this game." Now at this point they have a difference of opinion. He learned one way, she learned another.
     But then he would go one step further, get a book of card game rules, and show her the relevant one. In essence he was making an exclusive truth claim that the rule book, an external source of authority, represented the correct way to play, and that she should follow it. My question for 2013 readers is do you feel/believe that this is legitimate or illegitimate, valid or invalid? Should she abide by the rule book or can she say, "I learned it this way. I don't care what the rule book says."
     What if he were to say to her, "I love you so we will play the way you learned it." What do we think about that?
     Finally, let's posit a slightly different scenario. Let's say that the two of them invite two other couples over. They have a nice dinner and conversation. Afterwards someone says, "Let's play cards.' They agree on a particular game, but as they sit down to play they discover that each of the six has learned a different way to play it. Now is it appropriate to bring out the rule book, or should each one maintain their own understanding of the truth and play how they individually believe should be done?
     As Christians, do we really believe in absolute, universal truth, or can we believe whatever we want?