If not for those specific circumstances… could they have ever been legally divorced?

No.

As I’ve explained five times: there are no penalties for things that can’t happen. When the state refused to let people divorce - which they did, at their discretion, by default, for centuries - people just stayed married. It wasn’t a crime, it was not legal.

Divorce wasn’t legal the way marrying a horse isn’t legal. You can have the ceremony. It doesn’t count. Per your chosen definition: it has no formal status derived from law. Moving goalposts is what you’re about to do to pretend I haven’t given you everything you fucking asked for.

You declared “you had a legal right to divorce from the founding of this country.” Rights are the thing where you have to get beaten to exercise them, yeah? Nowadays you have a right to divorce. In the past times, it took some heinous shit to “escape the bonds of marriage.” You had to beg the church, or the state, and they could just say no. They almost always said no.

And there was nothing you could do.