VATICAN CITY (CNS) -- The COVID-19 pandemic has been tough on families, but with extra patience and faith, bonds can grow stronger, Pope Francis wrote in a letter released on the feast of the Holy Family.

"Marriage, as a vocation, calls you to steer a tiny boat -- wave-tossed yet sturdy, thanks to the reality of the sacrament -- across a sometimes stormy sea," he told couples in the letter published Dec. 26.

Like the disciples who were foundering on the Sea of Galilee, couples must keep their eyes fixed on Jesus, he said. "Only in this way, will you find peace, overcome conflicts and discover solutions to many of your problems. Those problems, of course, will not disappear, but you will be able to see them from a different perspective."

Reciting the midday Angelus prayer with visitors in St. Peter's Square Dec. 26, Pope Francis said he had written the letter as a "Christmas gift" to married couples during the celebration of the "Amoris Laetitia Family" Year, a year dedicated to re-reading his 2016 exhortation on marriage and family life.

In his Angelus talk, the pope commented on the day's Gospel reading about a 12-year-old Jesus staying behind in Jerusalem and making Mary and Joseph frantic.

"In the Gospel, we see that even in the Holy Family things did not all go well: There were unexpected problems, anxiety, suffering. The Holy Family of holy cards does not exist," he said.

When Mary and Joseph find Jesus in the temple and ask him why he worried them so, he tells them, "Did you not know that I must be in my Father's house?"

Mary and Joseph do not understand, the pope said. "They need time to learn to know their son. That's the way it is with us as well: Each day, a family needs to learn how to listen to each other to understand each other, to walk together, to face conflicts and difficulties."

In his letter to families, like in "Amoris Laetitia," Pope Francis paid tribute to the strength and tenacity of couples as they face real difficulties together on the journey of life.

Like Abraham, called by God to set out to an unknown land, he wrote, with the pandemic "we, too, have experienced uncertainty, loneliness, the loss of loved ones; we, too, have been forced to leave behind our certainties, our 'comfort zones,' our familiar ways of doing things and our ambitions, and to work for the welfare of our families and that of society as a whole, which also depends on us and our actions."

The pandemic lockdowns, quarantines and periods of isolation "meant that there was more time to be together, and this proved a unique opportunity for strengthening communication within families," the pope said. But that also demanded patience.

"It is not easy to be together all day long, when everyone has to work, study, recreate and rest in the same house," he said.

When nerves are frazzled, the pope said, try to put the needs of others first and re-read the hymn to love from 1 Corinthians 13 "so that it can inspire your decisions and your actions" and "the time you spend together, far from being a penance, will be become a refuge amid the storms."

Pope Francis also told married couples, "Don't be ashamed to kneel together before Jesus in the Eucharist, in order to find a few moments of peace and to look at each other with tenderness and goodness."

And, for couples whose problems were exacerbated by the pandemic and led to a breakup, Pope Francis said, "I would like them, too, to sense my closeness and my affection."

But he urged them to be civil to one another, especially in front of their children so that the pain of seeing their parents separate is not made worse by seeing them constantly fighting.

"Children are always a gift," the pope wrote. "They are thirsty for love, gratitude, esteem and trust."

Parents must pass on to their children "the joy of realizing that they are God's children, children of a Father who has always loved them tenderly and who takes them by the hand each new day," he said. "As they come to know this, your children will grow in faith and trust in God."

Addressing engaged couples, Pope Francis said he knows the pandemic has been especially hard for those trying to plan a future together.

"In your journey toward marriage," he told them, "always trust in God's providence, however limited your means, since at times, difficulties can bring out resources we did not even think we had. Do not hesitate to rely on your families and friends, on the ecclesial community, on your parish, to help you prepare for marriage and family life by learning from those who have already advanced along the path on which you are now setting out."

The 85-year-old pope also expressed his affection to grandparents, especially those who are feeling isolated or alone. He urged families to make greater efforts to be with them or at least be in touch with them.