Jesus said divorcing and entering a new marriage were not an option open t to any of us. But, Moses had allowed it in some cases. As well, we should not condemn anyone to continue in a relationship that presents a real danger to his or her life.
Our Lord's prohibition would keep one from giving the name of marriage to what from the start is regarded as temporary.
Like, once I formed a friendship with a college boy for whom his parents had contracted what for what they saw as an advantageous marriage. But with that son determined on marrying another; the family allowed him to enter into a Five Year Marriage with that Sweetheart. The boy showed me a copy of the invitation they ha d printed for that five-year marriage.