Sex is for marriage, and marriage is for life. In adultery you are married but betray your spouse by having an affair, by fantasizing about someone or panting after pornography, or by divorcing a faithful spouse and marrying someone else. In fornication you are single but selfishly seek sex without a lifelong marriage commitment, through impure dating, prostitution, or "living together." In homosexualism you want someone of the same gender to satisfy your romantic and sexual longings. God forbids all such sins. He commands his people to have sexual union only in a faithful marriage to a fellow Christian of the opposite sex, or else to remain single and abstain from sexual relations.
If you are a Christian, Jesus didn't just buy your soul; he bought your body. You body is the Holy Spirit's temple. Indeed, your body is a member of Christ himself. So before doing something with your body, be sure it pleases the Lord within you and not just your sinful nature. Once you unite yourself to the Lord in spirit, you must not unite your body to anyone unless that person is a spouse of the opposite sex who is also united to Jesus in spirit.
The bodies of Christians belong to Jesus, and the marriages of Christians are designed to display the love of Jesus and his Church. A loving husband sacrifices anything to help his wife, as Jesus did for his church. A faithful wife submits to her husband in love, as the church submits to Christ her head (Ephesians 5:21-33). Honoring marriage honors Jesus.
PRAYER--Lord, you bought us and built us to be your temple. Forgive our sins; cleanse our hearts; deal with our disorders. Help us, married or single, to glorify you with our bodies. Amen.