I'm Catholic and my fiance is Greek Orthodox. We have talked about getting married in a Catholic church. One priest told us that if my fiance gets married in a Catholic church he will become excommunicated by the Greek Orthodox church but he went further on to say that if I get married in a Greek Orthodox church it would be fine provided I get permission from my church. But my priest stated that it was okay for my fiance and I to have the ceremony in the Catholic church provided we agree to raise our children Catholic. I don't know what to go by. As much as I would like a Catholic ceremony I would not want my fiance to get excommunicated by his church unknowingly.
It is a wise and loving gesture for you to want to avoid endangering your future husband's church membership. In supporting his faith tradition, you already have a good foundation for marriage.
From the little we know about Greek Orthodox canon (church) law, it would be considered a sin for him to marry outside his church and therefore he would not be able to receive the sacraments. Whether he would actually be excommunicated, we aren't sure. However, this would definitely be a detriment to his spiritual growth.
You can be married in the Greek Orthodox church with proper dispensation from the Catholic Church, but you will not be allowed to receive the Eucharist together. Under Greek Orthodox canon law, he will not be allowed to receive communion at a Catholic Church, should you attend those services during your marriage.
If this seems too restrictive, you may want to have a talk with a Greek Orthodox priest and also a Catholic priest. They will be best able to advise you on any pastoral decisions available to interchurch couples.