Is a wife's withdrawal of money from her husband's account without his knowledge, to pay off a debt she owes—given that the husband is aware of her debt and refuses to pay it—considered theft?

A husband is not obligated to pay his wife's debt unless he does so voluntarily. If a husband spends on his wife and children in a reasonable manner, then it is not permissible for the wife to take anything from his money without his permission, as this is a betrayal of trust. A woman is a guardian in her husband's home and is responsible for her guardianship. A woman should not spend anything from her husband's household without his permission. Therefore, your taking from your husband's money to pay your debt without his permission is a forbidden betrayal that necessitates repentance and returning what you took to him. What one takes, one must return until it is discharged. If you return the money to him, even without his knowledge, or inform him and he absolves you of it, then your conscience will be cleared.