Story highlights Pope Francis: "Dear young people, don't be afraid to marry"

He takes Valentine's Day questions from young couples about having a happy marriage

Thousands of young engaged couples gather in St. Peter's Square to hear him

He says couples must build their love together and let it grow

In a gesture toward the romance of Valentine's Day, Pope Francis on Friday gave his advice on how to have a happy marriage before thousands of young engaged couples.

The unprecedented event, held under brilliant winter sunshine in a packed St. Peter's Square in Vatican City, may reflect Francis' desire to be closer to ordinary people's lives.

Three couples were able to put their own questions directly to the Pontiff before being blessed.

His answers were shared with the 25,000 or so people from around the world spread out in the square before him.

The first young couple to speak explained how they had decided to get married. "We didn't want to give in to the easy way of not committing," the man said.

The couple asked the Pontiff to give them his advice on how to make a lasting marriage.

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Francis, himself committed to lifelong celibacy as a Catholic priest, said that many people are afraid these days to make "definite decisions" and long-lasting choices -- but that it can be done.

'Don't be afraid to marry'

"Today, everything is changing rapidly and nothing lasts for long. This sort of mentality leads so many who are getting ready for marriage to say they will be together for as long as love lasts," which can lead to divorce, he said.

Love has to be built together, he said, not alone. "To build such a thing means to help your love grow," he said.

"Dear engaged people, you are getting ready to grow together, to build a home, to live together for good. Do not just base it on those feelings that come and go, but on the rock of true love that comes from God," he said.

Francis also took to Twitter to encourage those who are in love to take the plunge and tie the knot.

"Dear young people, don't be afraid to marry. A faithful and fruitful marriage will bring you happiness," he said on his official @Pontifex account.

Don't go to bed angry

A second couple in St. Peter's Square told Francis of how their love and commitment had changed their lives, before the woman asked for the Pope's advice on how to live together day to day.

"Living together is an art. It's a patient art, it's a beautiful art, it's fascinating," Francis replied.

He spoke of the need to communicate with respect and attention, "to request politely so that you enter with courtesy into the life of the other."

That isn't easy, he said. Each half of the couple must learn to say thank you, and to apologize for his or her mistakes.

"We all know there isn't a perfect family, neither a perfect husband nor a perfect wife. Of course, we are not talking about the perfect mother-in-law," he joked.

"Do not end any day without asking each other for forgiveness, having peace back in your house and your family," he said. "Never end a single day without being at peace with each other. This is the secret in order to preserve love."

The third couple's question dealt with how to celebrate their marriage.

Francis said the key thing was not to have a wild party, though the celebration is important, but to feel the presence of Jesus. The dress, flowers and food are important, but only if the couple are there in a true spirit of love, he said.

St. Valentine was a third-century Roman priest who is widely believed to have been martyred on February 14 for his beliefs. He has since become the patron saint of love and engaged couples.