Christ and the Church
Ephesians 5:32 This is a great mystery, but I speak concerning Christ and the church.
Paul is saying that he wants to be clear about the things he just got finished writing. The references that he made were so that we would better understand the relationship between Jesus Christ and the church. So when a woman and man marry it symbolizes that future relationship. This is why God gave us this divine institution, so that we could better understand our destiny