Apparently if a man takes a woman who has con-sensually given herself to her first partner in the past and he is still alive ; That is Adultery unless a widow.
Once a woman allows herself to be taken by a man and her hymen has been broken "shedding of blood" or essentially it is her first time ; they have become one flesh and entered into a covenant. With Spirit, Water, and Blood bearing witness.
It seems a marriage is only ended if someone becomes a widow or infidelity where it seems like the the covenant is infringed upon.
Perhaps if a man does not fulfill his role as a husband or a woman does not fulfill her role as a wife then further guidance is needed
Ideally Man was created with one help mate and the sons of man are to have one helpmate; The law allows men to have multiple wives within reason and circumstances. Our Lord prefers us to have one partner for our benefit and simplicity if we decide to have each other
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I cannot discern how marrying someone who has been married twice before would not be considered Adultery unless the past two spouses of the Man died, the husband's two wives consent to this, or the past two wives committed extramarital affairs so he divorced them and the woman that is about to marry him is a virgin.
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Act 17:30 And the times of this ignorance God winked at; but now commandeth all men every where to repent:
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Rom 7:6 But now we are delivered from the law, that being dead wherein we were held; that we should serve in newness of spirit, and not in the oldness of the letter.
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If reconciliation is impossible then it seems one could marry or remarry however with further knowledge and experience one would be even more expected to remain committed unless death or covenant infringed upon thru extramarital affairs.
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Rev 2:18 And unto the angel of the church in Thyatira write; These things saith the Son of God, who hath his eyes like unto a flame of fire, and his feet are like fine brass;
Rev 2:19 I know thy works, and charity, and service, and faith, and thy patience, and thy works; and the last to be more than the first.
Rev 2:20 Notwithstanding I have a few things against thee, because thou sufferest that woman Jezebel, which calleth herself a prophetess, to teach and to seduce my servants to commit fornication, and to eat things sacrificed unto idols.
Rev 2:21 And I gave her space to repent of her fornication; and she repented not.
Rev 2:22 Behold, I will cast her into a bed, and them that commit adultery with her into great tribulation, except they repent of their deeds.
Rev 2:23 And I will kill her children with death; and all the churches shall know that I am he which searcheth the reins and hearts: and I will give unto every one of you according to your works.
Rev 2:24 But unto you I say, and unto the rest in Thyatira, as many as have not this doctrine, and which have not known the depths of Satan, as they speak; I will put upon you none other burden.