18 Every man who puts away his wife and marries another is an adulterer, and he too is an adulterer, that marries a woman who has been put away.There's not a lot of wiggle room here. A valid sacramental marriage cannot be ended by anything except death. When a diocesan tribunal makes a declaration of nullity, what they are saying is that there was no valid sacramental marriage there in the first place. It is not a dissolution of a marriage that actually existed. It's true that the annulment process has been so bastardized that most lay people think of it as a Catholic divorce now, but that is not the case.
I once asked a priest who has worked for the marriage tribunal if the annulment process was systemically broken, or if there really were that many Catholics living in objectively invalid marriages. Without hesitation he replied, "Both." I will be very surprised indeed if the Synod on the Family discusses that, as that is the real scandal.