Your vision of what you both want out of this relationship is in direct opposition to the reality that you're living out together, and that fact could be a source of real disappointment and disillusionment during this two-year period. Whatever you each do to try to bring the relationship closer to your fantasies won't work very well; reality checks will come in all shapes and sizes now, and you just won't be able to get used to them. The foundation of your whole relationship even seems to be shifting; what you thought was solid between you -- a shared sense of values, perhaps, or compatible senses of humor, or a great sexual connection -- suddenly seems to be slipping away.
What is your relationship even based on? This is a question that will come up again and again for each of you through the course of this period, and it will be a tough one to answer. But look on this period as a growth opportunity, if you can. Answering tough questions about why you're together will give you an even more solid idea of your bond. And accepting the reality of your connection, rather than trying to pretend it's something more ideal than it is, will make you both happier in the long run.