1 Corinthians 7:10-11: To the married I give charge, not I but the Lord, that the wife should not separate from her husband (but if she does, let her remain single or else be reconciled to her husband) — and that the husband should not divorce his wife.
Mark 10:11-12: And he said to them, “Whoever divorces his wife and marries another, commits adultery against her; and if she divorces her husband and marries another, she commits adultery.”
Luke 16:18: “Every one who divorces his wife and marries another commits adultery, and he who marries a woman divorced from her husband commits adultery.”
Matthew 19:9: “And I say to you: whoever divorces his wife, except for unchastity [actually incest] and marries another, commits adultery; and he who marries a divorced woman, commits adultery.”
The meaning in Matthew is not that the innocent party is guilty if a spouse commits adultery. When circumstances are out of control, the wronged party may be allowed by the Church to live apart from the adulterous spouse. However, if truly married, neither can marry another validly as long as one of them lives.
For more such reading, contact me about getting my book, DEFENDING THE CATHOLIC FAITH.