The answer
Sex before and after marriage is adultery. Sex inside of marriage is the right and pure thing; it is the only sex that can be a fruit of love and a way for love. It will increase the love between the two partners, and it will lead them to more spiritual love; because the Lord is the third person living with them and unifying them: man, woman, Jesus Christ - this is a true Christian marriage. If there is no Jesus Christ, it will just be a man-woman human relation, and it can be broken at any time. So have the Lord inside your life, inside your heart, inside your home, and for sure you will have a very happy life in marriage.
H.G. Bishop Moussa