Because it's tells you what is love and you fell in love in that woman you really like her and he like you to be forever by every challenges no matter it's hard or not hard but you're still protecting each other and if you having a fight with your wife that it didn't mean to each other but you are still can forgive each other because you promised each other that you won't let go your wife to be alone forever and that's how they learned how much really important to love each other but you still not giving up to each other that you gave everything to her but is not really to give up.