Not much notice has been taken of Ratzinger's article on the dogmatic-historical aspects of the indissolubility of marriage and their relevance to present teaching and pastoral practice: "Zur Frage nach der Unauflöslichkeit der Ehe: Bemerkungen zum dogmengeschichtlichen Befund und zu seiner gegenwärtigen Bedeutung" in Ehe und Ehescheidung: Diskussion unter Christen, Kösel-Verlag, München, 1972. Perhaps that is to some degree because many communities and pastors "solve" the problematic simply by ignoring the Church's teaching and directives.
Unlike the 1970 letter on celibacy, of which Ratzinger was a co-signer, which simply called for a re-consideration of the discipline of celibacy, not for a change in it, as has often been claimed, this article actually seems to suggest that a change in discipline (not doctrine) is appropriate, inasmuch as the Church should allow for some flexibility in certain cases in dealing with persons living in a second marriage.
Ratzinger traces two lines in the Church's doctrine and practice: on the one hand, the consistent conviction that a sacramental marriage cannot cease except by the death of one or both of the spouses, thus excluding the possibility of a second marriage; on the other hand, a recurring toleration of illicit (and invalid/non-sacramental/non-Christian) marriages in order to avoid still worse evils.
He sees the Orthodox way, in which these tolerated exceptions become the norm, as mistaken, yet nonetheless proposes that some room for such pastoral toleration of second marriages should be given. Concretely, he proposes that when the marital life of the first marriage cannot be restored, a second "marriage" has existed for a long time, with children and the resulting obligations to them, and in which the life of faith is manifest, it should be possible for a pastor and a Church community to permit this couple to receive Holy Communion.
Read the entire article: On the Question of the Indissolubility of Marriage