The Vatican has released a 40-page doctrinal document titled "One Flesh – In Praise of Monogamy," signed by Pope Leo XIV and written by Cardinal Víctor Manuel Fernández, which affirms the Catholic Church's teaching that marriage is an exclusive union between one man and one woman.The document distinguishes between polygamy and polyamory, addresses their cultural contexts, and emphasizes that practices like polygamy, adultery, and polyamory arise from misunderstandings about relationship depth.It also highlights marriage’s enduring nature, the unitive aspect of sexual relations, and the importance of personal space and mutual belonging for long-term intimacy and trust.