Saying there is no such thing as "express marriage," Pope Francis expounded on the love between a man and a woman during his weekly general audience following Ireland's vote in favour of gay marriage last week.

The Pope still has not personally commented on the milestone event in Ireland although Vatican Secretary of State Cardinal Pietro Parolin called the Irish vote "a defeat for humanity" a day before the pontiff made his remarks on love and marriage.

Speaking to a weekly general audience, the 78-year-old leader of the world's 1.2-billion Roman Catholics said love between a man and a woman entails a journey that requires work, maintaining that there are no shortcuts to marriage, the Catholic News Agency reported on Wednesday.

"Marriage, as a vocation from God, is not just a relationship based on attraction and feelings, of a moment, of something short. It requires a journey," the pontiff told his audience, many of whom were engaged couples.

The pope's emphasis on engagement is part of his continuing catechesis on the family leading to the World Day of Families in September and the Synod of Bishops on the Family in October.

"...We have to work for love. We have to journey in the relationship of love between a man and a woman until it learns (and) until it grows," he said.

The journey of marriage "establishes a very strong and lasting partnership, which makes two lives one, a true miracle of human freedom and the grace of God."

Pope Francis said lifetime love cannot be hastened.

"The alliance of love between a man and a woman, an alliance for life, cannot be improvised, and is not made in a day," the Pope said.

The Pope warned that stages in the journey of love "should not be burned" amid the widespread culture in society that wants "everything and immediately." This degrades love into an object of consumption, which cannot create a solid foundation for a "vital" commitment as marriage.

Engagement allows couples to know each other deeply while preparing for the "beautiful yet demanding enterprise of marriage."

This process is crucial "so that the responsible decision for something so big – something which can't be bought or sold – matures."

"Love itself demands this preparation, which makes possible a free, generous and sober decision to enter into a life-long covenant of love," said the pope.

Couples who finish the marriage preparation courses required by priests are thankful for the lessons they learn, he said.

"Today more than ever it's necessary to revalue engagement as an initiation to the surprise of the spiritual gifts with which God blesses and enriches the family."