Not specifically addressed here about the “marital debitum” per se - but it can assist in thinking about such. He even used the word “debitum”
“According to the different relationships and different aspects, justice has obtained more appropriate definitions throughout the centuries. Hence the concept of justice: communicative, distributive, legal and social. All this testifies what a fundamental significance justice has for the moral order among men, in social and international relations. It can be said that the very meaning of man’s existence on earth is bound up with justice. To define correctly “how much is due” to each one from all and at the same time to all from each one, “what is due” (debitum) to man from man in different systems and relationships—to define, and above all to put into practice!—is a great thing, through which every man lives, and thanks to which his life has a meaning.”
"Each of us, then, must be able to live in a context of justice and, even more, each of us must be just and act justly with regard to those near us and those who are far away, with regard to the community, to the society of which one is a member… and with regard to God.
Justice has many references and many forms. There is also a form of justice which regards what man “owes” God. This is a vast subject in itself. I will not develop it now, although I cannot abstain from indicating it.
Let us give our attention, meanwhile, to men. Christ left us the commandment to love our neighbour. In this commandment, everything that concerns justice is also contained. There can be no love without justice. Love" surpasses" justice, but at the same time it finds its verification in justice. Even a father and a mother, loving their own child, must be just in his regard. If justice is uncertain, love, too, runs a risk.
To be just means giving each one what is due to him. This concerns temporal goods, of a material nature. The best example here can be remuneration for work or the so-called right to the fruits of one’s own work or of one’s own land. But to man is due also his good name, respect, consideration, the reputation he has deserved. The more we know a man, the more his personality, his character, his intellect and his heart are revealed to us. And the more we realize—and we must realize!—with what criterion to “measure him” and what it means to be just towards him.
It is necessary, therefore, to deepen our knowledge of justice continually. It is not a theoretical science. It is virtue, it is capacity of the human spirit, of the human will and also of the heart. It is also necessary to pray in order to be just and to know how to be just.
We cannot forget Our Lord’s words: “The measure you give will be the measure you get” (Mt 7:2)."
(St) JOHN PAUL II
GENERAL AUDIENCE
Wednesday, 8 November 1978