1 Corinthians 7:7–9: Is Singleness a Sin?
Paul does not treat singleness as sin. He calls the unmarried and widowed state good, names both marriage and singleness as gifts God distributes differently, and still tells those without self-control to marry.
1 Corinthians 7:10–16 on Separation and Divorce
Paul treats the command against a spouse leaving as the Lord's own word, not his own counsel, and he keeps the door open after a separation. Where an unbelieving spouse departs, the believer is not bound, and the outcome is left with God.