Pope Benedict has said the growing number of loveless relationships may be behind declining birthrates in the developed world.
The pope also said on Friday that an "eclipse of love" and lack of moral guidance threatened the intellectual and spiritual development of future generations of children.
"Perhaps the lack of such creative and forward-looking love is the reason why many couples today choose not to marry, why so many marriages fail, and why birthrates have diminished," the pope said in a message to a meeting of the Vatican's Pontifical Academy of Social Sciences.
"It is children and young people who are often the first to experience the consequences of this eclipse of love and hope. Often, instead of feeling loved and cherished, they appear to be merely tolerated."