more more MORE!!!

Part of the argument against consumerism and continually wanting more "toys" is that you will never be satisfied, you will always want more, more, more. This seems to translate to other areas of life (all?). I have a great relationship going, but then I want MORE. I want to get an even better relationship. Where would this end? Could it end? Is it better at all to keep wanting more and getting to "higher" stages? How can this be related to Nietzsche's Will to Power?