My first wife and I have discussed plural marriage and even though she agrees it is Biblical, she won't give up what she's believed her whole life and mentions divorce if I want a plural marriage.
It would have been nice to know the rest of this story.
I have always thought that the study of polygamy led me to study what God thought of marriage in general and that it improved my monogamous marriage. One thing that quickly became obvious to me is that while God says nothing against polygamy, he says a whole lot against divorce. Why otherwise faithful Christians believe divorce to be an option has since been a huge mystery to me. For some reason polygamy is really horrible, but divorce is merely unfortunate, despite what the Bible does or does not say about the two practices.
In fact this is one of my go to statements when another Christian asks me about polygamy. "The Bible says nothing against polygamy but anyone who practices it would be shunned, but churches are filled with divorced people and no one thinks twice about that even though the Bible very clearly says that God hates that. There is a major disconnected there about how we think of marriage compared to how God thinks of it. I support how God thinks of it."
I think a study or marriage and divorce would be excellent for any shaky Christian marriage. If nothing else, it will illuminate if we are Christians merely by culture or if we are truly following God.