Your own integrity does not depend on that of the honor of anyone else.
In God's eyes, when He jins them toget hhethe marriage is not ended until you or she dies. It's that simple.
Until the union is consummated by sexual congress, marriage exists only as a mutual promise of exclusive ownership by one of the other by virtue of shared flesh (1 Cor. 7:4)--the two have not joined flesh to flesh, gamete to gamete, with the tokens of the bride's virginity demonstrated (or NOT) to prove (disprove) her continence. Whatever or however the Jewish rabbis or Gentile customs, Jesus supersedes them by going back to Genesis 2 and the age of innocence to point out what the circumstances are to which repudiation applies in His eyes. But after congress, no further wiggle room for divorce, no further man putting asunder what The Godhead hath joined together. Separation to prevent physical or verbal abuse of one by the other is OK (per Paul's NT-explained OT-contained doctrine), but breaking the covenant after it has transitioned from thought to reality, no.
It is not whether either ofthe participants kept their word and mutual fidelit; it iw about God keeping His.
Bro, I believe you believe what you wrote, but I believe Christ's words about the porneia exception mean something different than you are saying.
Best
(you must have been typing fast! I don't know many words in your post!)