Before we can answer this question, we must understand two important truths from Scripture. First, God created marriage as a binding covenant for life between one (biological) man and one (biological) woman. Jesus said in Matthew 19:4-6, “Have you not read that He who created them from the beginning made them male and female, and said, ‘For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh’? So they are no longer two, but one flesh. What therefore God has joined together, let no man separate.”
Second, the only allowances God gave for divorce are infidelity and abandonment (by an unsaved spouse). Jesus said in Matthew 19:8-9, “Because of your hardness of heart Moses permitted you to divorce your wives; but from the beginning it has not been this way. And I say to you, whoever divorces his wife, except for immorality, and marries another woman commits adultery.”
Additionally, Paul wrote in 1 Corinthians 7:12-15, “If any brother has a wife who is an unbeliever, and she consents to live with him, he must not divorce her. And a woman who has an unbelieving husband, and he consents to live with her, she must not send her husband away. For the unbelieving husband is sanctified through his wife, and the unbelieving wife is sanctified through her believing husband; for otherwise your children are unclean, but now they are holy. Yet if the unbelieving one leaves, let him leave; the brother or the sister is not under bondage in such cases, but God has called us to peace.”
Therefore, if a married couple obtains a divorce for biblical reasons, they are no longer married to each other legally or in God’s view. However, if they divorced for reasons outside of God’s allowances, they are still married before God, regardless of their legal marital status.
Consequently, couples who divorce for unbiblical reasons and enter a romantic relationship with someone new commit adultery (even if they are legally wed to them) because they are still married to their “ex-spouse” in God’s eyes.
With that said, one might ask, “If someone gets divorced for unbiblical reasons and married someone else, wouldn’t that nullify their original marriage because adultery qualifies as an allowance for biblical divorce?” Technically, the answer would be yes and not result in perpetual adultery. However, the question’s premise misses the heart of marriage and God’s intention for it and should not be used to justify a divorce or as a means to "biblically" release someone from their marriage covenant.
I hope this information helps you understand how God sees marriage and what role divorce plays in dissolving or unaffecting that covenant.
