Ex-Polygamist or Polyamorous Woman Wanted

What I want to understand is why a woman who doesn't need to share her husband or lover would make that choice.

Equality, Freedom and Justice for All

The Committee on the Elimination of Discrimination against Women has stated, in its general recommendation no. 21 on equality in marriage and family life: “Polygamous marriage contravenes a woman's right to equality with men, and can have such serious emotional and financial consequences for her and her dependents that such marriages ought to be discouraged and prohibited”