IV. Offenses Against the Dignity of Marriage

2387
The predicament of a man who, desiring to convert to the Gospel, is obliged to
repudiate one or more wives with whom he has shared years of conjugal life, is
understandable. However polygamy is not in accord with the moral law.”
[Conjugal] communion is radically contradicted by polygamy; this, in fact,
directly negates the plan of God which was revealed from the beginning, because
it is contrary to the equal personal dignity of men and women who in matrimony
give themselves with a love that is total and therefore unique and
exclusive.”¹⁷⁹ The Christian who has previously lived in polygamy
has a grave duty in justice to honor the obligations contracted in regard to
his former wives and his children.

From The Catechism of the Catholic Church – rosary.team

Original Link: https://www.vatican.va/archive/ENG0015/__P87.HTM