You do realize that, contrary to popular parroted rhetoric, Christ is not addressing reason(s) for divorce. Nor is He commenting on the status of new marriages as being continual adultery. He is talking about how the process makes the two dead to each other covenant wise when its exercised to its fullest extent, meaning, when the wife marries another.
In case where a woman was caught in adultery, witnessed by two or more, there would be a stoning of her and the other man.
But what happens when there is no physical act of adultery, yet, either the husband or the wife is not committed to the marriage, when he or she is committing adultery in small degrees? In that case, the bill of divorce and pursuant marriage of the wife makes the two "dead" to each other the same way that a stoning would. Reason: "for that [is] abomination before the LORD: and thou shalt not cause the land to sin, which the LORD thy God giveth thee [for] an inheritance."Deut 24:4