Let me give you some verses for clearity
New International Version
But I tell you that anyone who divorces his wife, except for sexual immorality, makes her the victim of adultery, and anyone who marries a divorced woman commits adultery. Matthew 5:32
1 Corinthians 7:15
But if the unbelieving partner separates, let it be so. In such cases the brother or sister is not enslaved. God has called you to peace.
1 Corinthians 7:10-11
To the married I give this charge (not I, but the Lord): the wife should not separate from her husband (but if she does, she should remain unmarried or else be reconciled to her husband), and the husband should not divorce his wife.
Mark 10:11
And he said to them, “Whoever divorces his wife and marries another commits adultery against her,
Side note: If you remarry the person who remarry and their spouse have both committed adultery against you and the wrath of God will be upon them.
1 Corinthians 7:39
A wife is bound to her husband as long as he lives. But if her husband dies, she is free to be married to whom she wishes, only in the Lord.
Matthew 5:31-32 ESV / 73 helpful votes
“It was also said, ‘Whoever divorces his wife, let him give her a certificate of divorce.’ But I say to you that everyone who divorces his wife, except on the ground of sexual immorality, makes her commit adultery, and whoever marries a divorced woman commits adultery.
Deuteronomy 24:1-4 ESV / 53 helpful votes
“When a man takes a wife and marries her, if then she finds no favor in his eyes because he has found some indecency in her, and he writes her a certificate of divorce and puts it in her hand and sends her out of his house, and she departs out of his house, and if she goes and becomes another man's wife, and the latter man hates her and writes her a certificate of divorce and puts it in her hand and sends her out of his house, or if the latter man dies, who took her to be his wife, then her former husband, who sent her away, may not take her again to be his wife, after she has been defiled, for that is an abomination before the Lord. And you shall not bring sin upon the land that the Lord your God is giving you for an inheritance.