The key to a long and successful marriage is extensive preparation and support even into the first few years after their wedding, Pope Francis said Saturday. Speaking to parish priests in Rome attending a course on the marriage annulment process, Francis said that young couples need to do more than just attend a few marriage preparation classes.

“I ask myself how many of these youth who come to marriage preparation courses understand what ‘marriage,’ the sign of the union of Christ and the Church, means,” he said, according to Catholic website Crux. “They say yes, but do they understand this? Do they have faith in this?”

Preparation, said Francis, was more than just “two or three meetings and then go forward.” Instead, he instructed priests to make couples fully aware of the significance of the union.

“This testimony is put into practice when you prepare marriage partners for marriage, making them aware of the profound importance of the step they are about to take,” he said.

Francis also again showed his more flexible approach by telling the priests to offer the same level of support for those couples who choose to live together without marrying.

“Spiritually and morally-speaking,” he said, reported Vatican Radio. “They are among the poor and little ones towards whom the Church wants to be a Mother who never abandons, but is close to them and takes care of them…So be tender and compassionate towards them.”

Similarly, Francis advised those priests attending the course not to judge but to instead support “those who realize the fact that their marriage is not a true sacramental marriage and want to leave this situation.”

Divorce remained a sin in the Catholic Church. However, last September Pope Francis endorsed a document written by priests in his native Argentina that said priests in some cases could offer the “help of sacraments” to aid the integration of divorced and remarried Catholics into the church.

The message, he said, was the correct interpretation of a reformist document called Amoris Laetitia he penned in April, which led to much debate and confusion within the Church.