VATICAN CITY (CNS) -- Because the Holy Spirit specializes in love and unity, Catholic couples should pray regularly for the Spirit to be present in their marriage, Pope Francis said.

"Where the Holy Spirit enters, the capacity for self-giving is reborn," the pope said at his weekly general audience Oct. 23, continuing a series of talks about the role of the Holy Spirit in the life of the church and its members.

While the pope explained the gifts the Holy Spirit gives to a couple through the sacrament of marriage, he repeatedly told visitors and pilgrims that the unity and love of parents are important for children's growth and happiness.

"How beautiful it is to hear a mother say to her children, 'Your father and I...,' as Mary said to Jesus when they found him at the age of 12 in the temple, and to hear a father say, 'Your mother and I...,' as if they were one," Pope Francis said. "How much children need this unity -- dad and mom together -- this unity of parents, and how much they suffer when it is lacking! How much children suffer when their parents separate."

But "to correspond to this vocation, marriage needs the support of the one who is the gift, indeed the quintessential giver," the Holy Spirit, the pope said.

Pope Francis said marriage preparation courses should include "spiritual preparation," particularly a discussion about the Holy Spirit's role within the Trinity and how invoking the Spirit's assistance can help couples.

St. Augustine, starting from "the revelation that 'God is love,'" taught that that implies there is "one who loves, one who is beloved and love itself that unites them," the pope said. "The Father is, in the Trinity, he who loves, the source and origin of everything; the Son is he who is beloved, and the Holy Spirit is the love that unites them."

No one would say that "such unity is an easy task, least of all in today's world," the pope said, but it is the plan God has for a husband and wife, so "it is therefore in their nature."

Asking the thousands of people present in St. Peter's Square to join him in praying for peace, Pope Francis said that "early this morning, I received the statistics regarding deaths in Ukraine: it is terrible! War does not forgive; war is a defeat from the beginning."

The Vatican had said Pope Francis met in the morning with U.S. Defense Secretary Lloyd J. Austin III, who had attended the pope's Mass and canonizations Oct. 20 and then traveled to Ukraine before returning to Rome for his meeting with the pope.

The pope also told the crowd that "the investments that yield the most today are in weapons manufacturing. Profiting from death!"

"Let us pray to the Lord for peace, may he give peace to all, to all of us," he said. "And let us not forget Myanmar; let us not forget Palestine, which is suffering inhumane attacks; let us not forget Israel and let us not forget all nations at war."