Is the wife sinful for refusing her husband's marriage to another, and how can she be convinced of this, especially since the husband fears falling into sin if the marriage does not take place?

A husband has the right to marry up to four women, provided he treats them justly and is able to provide for their expenses, housing, and companionship, as Allah Almighty says: "Then marry such women as seem good to you, two, three, or four; but if you fear that you will not be able to deal justly (with them), then only one." When polygyny is practiced according to its conditions, it solves many societal problems. As for a wife using the law to prevent her husband from marrying another, if she stipulated this in the marriage contract, she has the right to use the law; if she did not stipulate it, then it is not permissible for her to do so. The questioner is advised to fear Allah and avoid this man, who is a stranger to her.