Ok that was quite a long post you made, so I will answer in 2 separate posts.
First, concerning Hermas. Are you referring to this quote:
""I charge you," said he, "to guard your chastity, and let no thought enter your heart of another man's wife, or of fornication, or of similar iniquities; for by doing this you commit a great sin. But if you always remember your own wife, you will never sin. For if this thought enter your heart, then you will sin; and if, in like manner,you think other wicked thoughts, you commit sin. For this thought is great sin in a servant of God. But if any one commit this wicked deed, he works death for himself. Attend, therefore, and refrain from this thought; for where purity dwells, there iniquity ought not to enter the heart of a righteous man." I said to him, "Sir, permit me to ask you a few questions.""Say on," said he. And I said to him, "Sir, if any one has a wife who trusts in the Lord, and if he detect her in adultery, does the man sin if he continue to live with her?" And he said to me, "As long as he remains ignorant of her sin, the husband commits no transgression in living with her. But if the husband know that his wife has gone astray, and if the woman does not repent, but persists in her fornication, and yet the husband continues to live with her, he also is guilty of her crime, and a sharer in her adultery." And I said to him, "What then, sir, is the husband to do, if his wife continue in her vicious practices?" And he said, "The husband should put her away, and remain by himself. But if he put his wife away and marry another, he also commits adultery." And I said to him, "What if the woman put away should repent, and wish to return to her husband: shall she not be taken back by her husband?" And he said to me, "Assuredly. If the husband do not take her back, he sins, and brings a great sin upon himself; for he ought to take back the sinner who has repented...In this matter man and woman are to be treated exactly in the same way.–The Shepherd 4:1-10. (I copied it from this paper
https://marriagedivorce.com/pdf/Restoration-of-Christian-Marriage.pdf)
Now, nolidad, it is your stated interpretation that remarriage is only not permitted because it blocks repentance. I will put forward something different.
What I see in this passage is something that we never hear about today. What if the wife persists in sex outside marriage? The husband is still one flesh with her, and therefore one body. So he is partaking in her sin - and he has to separate from her as long as she commits this sin. So far does the one flesh principle go. I believe this is a reiteration of the passage 1 Cor 6:16, where Paul talks about being joined to an harlot. I believe that 1 Cor 6:16 talks about being married to an harlot, but I have until now not met many folks who agree with me on that. And the reason for my interpretation is exactly that I read stuff like Hermas. You do know that at one time Shepherd of Hermas was part of the Bible?
So in my interpretation, this just goes to show how seriously the early Church took the principle of one-flesh.