I have looked in a few of the pre-Vatican 2 books that I have and, frankly, I can't find anything that mentions what the OP is asking, i.e., Catholic principles and teachings. This situation has never been the norm or even an ideal. I think, the Church really hasn't given general principles which govern the situation since it is, or, at least, should be an exception to the rule.
When we talk of a couple "living as brother and sister" today, we are generally talking about married people who are divorced and then enter into a second civil marriage and have children in the second adulterous marriage. For the children's sake, in order to raise them and care for them, the couple does not divide into two households but lives as brother and sister because they wish to reconcile with God and the Church.
One should remember that divorce and remarriage was relatively rare prior to the 1960s. This did not happen often. I'm not convinced that this "solution" was ever really contemplated before the explosion of divorce among Catholics since the 1960s. If it was, it would have been very quietly done and few, if any people, outside the house and the confessional would ever have even known about it. I am not sure whether or not this is really a good "solution" to the problem even now. I will leave the issue up to the judgment of those who are more qualified than I.
As stated above, there are a few instances in the Lives of the Saints where married couples lived as such for the glory of God. They did so with specific permission from the Church and for very specific reasons. I think most pre-Vatican 2 books that would discuss the issue at all would be in the various biographies of saints.
Topic: Living as brother and sister (Read 2657 times)