Is there an adulterous marriage?
Yeshua gave strict commandments showing us when divorce is not acceptable and when divorce, or a getting married again, constitutes adultery. Many believers have been breaking these commandments, and it is no wonder, since I never see these things taught in churches. Not teaching them just encourages more people to break them.
Yeshua declared:I say to you, That whosoever divorces his wife, except if it is for defilement, makes her a victim of adultery, and whosoever marries this divorced woman commits adultery.(1)
What does it mean to be the "victim of adultery"?
If a husband cheats on his wife, that defilement frees her from the marriage and allows her to marry another man instead. Likewise, the husband is free to divorce his wife if the wife cheats on him. (Details about the acceptable evidence below.)
However, what if there is no defilement involved, and the husband simply divorces her? Yeshua was very clear about this. Even though that act is like adultery in the eyes of God, the marriage itself is NOT yet dissolved. If any man were to suddenly marry her, then he commits adultery in God's eyes.(1) He may not realize it, and even the wife may not realize it, but it is still true nonetheless.
Until the earlier (legitimate) marriage is dissolved, each time that couple has sex they commit adultery. Only three things can dissolve the earlier marriage, and after being dissolved then that couple can be legitimately married. One is if the earlier husband re-divorces his wife, since at this point the divorce would be legitimate.
Two is if the earlier husband dies/disappears, and three is if the earlier husband cheats on her, allowing her to legitiately divorce him.
Whether the divorced woman has already re-married or not, or already engaged in any adulterous sex or not, as long as her earlier marriage remains in place then her only legitimate option is to remain pure, or if she has not been pure to immediately re-start being pure. She is bound to do this until her earlier marriage is dissolved. If she has already went and married another person (which she should not have), then from that point it is NOT appropriate for her eariler husband to take her back and reconcile with her.(2) He should re-divorce her, and then she will be free to do as she pleases. If she has not married another person already, and also does not have a legitimate cause to divorce her earlier husband, then her only acceptable option is to remain pure and, if she wants, reconcile with her earlier husband. She may have very legitimate reasons for not wanting to reconcile with him, but that alone does not mean she is free to marry another.
Adultery is a serious sin in God's eyes. Paul even lists it specifically as a sin that would theoretically exclude someone from salvation.(3) It is breaking one of the ten commandments. We cannot represent Yeshua well in this world if we are breaking this commandment. It is important that we understand what Yeshua taught, and apply it to our lives. I have not heard of churches ever, in any instance whatsoever, explaining to anyone that their marriage was called adulterous by Yeshua.
In discussing cheating, it is important to remember that you cannot divorce someone just because you strongly believe he (or she) has cheated. You should not think you have the liberty to gamble on your suspicions, and divorce your spouse in the hopes that your suspicions are correct (and hoping that you are not sinning). That is not how it works. You are free to withhold your body, or even get distance from your spouse, but divorce is different. It is only acceptable to divorce when the acceptable evidence is there. This is what Yeshua meant by the defilement exception. He meant defilement under the law of Moses, as the idea would have been applied by the Jews practicing the law of Moses.
If any of these things relate to your situation and you need help understanding anything, contact me for help understanding what is acceptable or not in your situation.
(1) Matthew 5:32
(2) Deuteronomy 24:4
(3) 1 Corinthians 6:9