My position has been that polygamy is allowed, just no divorce, no exceptions, that's my opponents view on divorce also, he just disagrees on polygamy. I don't know if you agree, but as an exercise, if you did, does this argument still work if no divorces are valid?
Methinks that most folks have the wrong idea about Yeshua's statement that it was because of the hardness of our hearts that Moses permitted divorce... they take it as some sort of a concession because He just knows we're going to sin anyway... This is problematic, theologically, to me. It doesn't seem coherent. Why not just make prostitution and abortion legal, then, since folks are going to do it anyway and at least if it is legal, then it isn't sin...
No, I think divorce is like another matter: The general trend in Scripture, as I read it, is that killing one's kids is not okay. Yet, there is a passage which instructs on taking a rebellious son to the elders to be put down. Why? Because, as my mind reasons, there are some situations that are worse than killing a particular individual... such as allowing them to live. Does God hate oxen? If He did, why are we instructed to not muzzle them whilst they tread the grain? Yet, an ox that thrusts and is not properly restrained against killing folks must be put down. So, I think what Yeshua was really saying was that some people are so hard-hearted against even their spouse that to force the other party to remain married to them (In certain, hard, specific circumstance - not just for any reason), divorce (which He hates) is permissible because there are other things which are worse.
For example: Joseph: Knows Mary is pregnant. Knows he didn't do it. Who are the witnesses she committed adultery against her betrothal? There can be none. Who is to say he didn't do it? He is his only witness. She, being an honest woman would probably have vouched for that much at least, but not that she had sinned against him. Let us imagine, now, however, that it wasn't Joseph and Mary. Let's say it was Reuven and Naomi. Reuven's little blue pills haven't been effective for a year. He's not been able to get it up, as it were. Naomi winds up pregnant somehow anyway. So, he knows he didn't do it. Yet, what can he prove in a Torah court? What did he witness? Did he catch her in the act? Will it be his word against hers?
I think, in such a case, or others, there is cause for Reuven to say: "Well, I can't prove I didn't impregnate you, but I KNOW I didn't. Get thee gone, woman!"
In such a scenario, is God permitting divorce, say, because He knows Reuven is going to be a hard-hearted asshole who just wants to trade Naomi in for a newer toy? Or is it because people like Naomi are hard-hearted enough to create situations from which there needs to be a righteous way out?