Why does the bride wear white?

The color white has long been a symbol of happiness, purity, and yes, even virginity. White is a symbol of being untainted by the world, and Christian brides wanting to wear white should have kept themselves from all impurities as described in the Bible for being pure. You are presenting yourself to your husband as pure and undefiled from the world, and wearing white is a symbol of the purity of which you have kept yourself throughout your life.
A bride wearing white is also a symbol of Christ’s relationship with his church. Many times in the Bible, Jesus refers to the church as the bride of Christ, and himself as the bridegroom. The church is a group of saved believers. Being saved, we as Christians are washed white as snow through the blood of Jesus Christ, being made pure (white) in the sight of God. The church presents themselves clean and pure from their sins in a lifetime partnership with God, much like the relationship of a man and wife. The bride of Christ has a personal relationship with God and a deep spiritual intimacy with him, also symbolising the relationship between a man and wife. We as Christians submit ourselves unto the Lord, and he cares for us.