The topic was discussed at Vatican assemblies in 2023 and 2024.
Polygamy is the practice of having more than one husband or wife at a time, while polyamory refers to engaging in multiple consensual romantic relationships at once.
“Polygamy, adultery, or polyamory are based on the illusion that the intensity of a relationship can be found in the succession of faces”, the document said.
It also laid out trends regarding love in the modern era, including “increasing divorce rates, the fragility of unions, the trivialisation of adultery, and the promotion of polyamory.”
The importance of marriage, being between a man and a woman, is emphasised throughout the document.
Another common theme in the document is that monogamy protects the equality and dignity of women, reported the Religion News Service.
Last month, the Pope and King Charles prayed together for the first time.
The King became the first monarch, as supreme governor of the Church of England, to take part in an ecumenical service with the Pope since the Reformation, when he visited the Vatican.