It gave them the freedom to re-marry, without the guilt of committing adultery.
When I look at passages like Deuteronomy 24:1-4, it seems to me that divorce was granted so that the divorced party could remarry, without becoming guilty of adultery.
I disagree that this limits our Lord's words to the engagement period, and not beyond.
What, then, do we say concerning Mark -12, which seems to teach that anyone who divorces and remarries is committing adultery?
Whether one can remarry, then, is determined by whether or not the divorce itself was biblical.