So what of either of them failed to honor that covenant? Did that constitute an annulment of the marriage?
Ahhhh
Yes, she could take a copy of the ketubah to a Rabbi...if she was living in the home. But she might find herself "put away" as well.
You have to remember that polygamy was mandated in some cases and desired in others. A wife's pecking order was determined by her husband. Polygamy wasn't considered abuse.
If she burned the cheapest dinner...it was considered grounds for divorce by some Rabbi. Only adultery was grounds for other Rabbi. (Same thing as here in America today)
And that exact question was put to Jesus in Matthew 19.
Jesus addressed the abusive situation surrounding the Put Away Wives.
People were fairly certain but didn't necessarily have proof of which women were put away wives. A put away wife could not marry or else she would be convicted of adultery and stoned (John 8)
So men would take advantage of the situation and had what was tantamount to wife swapping and divorce...marriage parlors where a person could get married for a few hours and divorced...or a few weeks.
It was a bit of a scandal.
But the true gist of what Jesus stated was that if a husband did not BEHAVE like a God fearing person then it's basically permitted. Jesus also gave a very, very strong caution about knowing exactly who it was that you were going to marry as well.
Remarriage statistics aren't really good.
Only 34% of second marriages are successful and 25% of third...the stats on successive marriages only gets worse.
Behavior of a husband or wife was the gist of what He said...faith wasn't...this was later explained more by Paul in one of his letters about wives being reconciled with their husbands.. Now it is interesting to note that Greek/Roman men often had a consort or girlfriend. (A publicly recognized relationship but not a spouse) So in his letter to Corinthian Wives on this subject it's rather interesting...it's later discussed in Timothy that men with Consort's were considered by Paul to be polygamists by referencing the consort as a wife which to Greeks was a somewhat insulting fashion.