Only, I have to say, in a very attenuated way if you are not Orthodox. The spiritual life of an Orthodox Christian is inextricably bound up with the Orthodox faith and the sacraments of the Church. You may fast with your husband-to-be: but for what? Fasting is a spiritual preparation for an Orthodox feast. But you will not be able to participate in that feast. And it is forbidden for him to participate in the services of your church. Consider this: you will never be able to share Easter together. Sorry to be blunt. Anyway, what's stopping you from becoming Orthodox?