Why is Misyar marriage, which violates the Sunnah and in which the woman gives up her rights, permitted, especially when a man secretly marries a non-Muslim woman and prefers her over his Muslim wife, tormenting her to push her to seek divorce?

Al-Misyar marriage is permissible according to Islamic law, whether it is with a Muslim woman or a chaste woman from the People of the Book. The husband's wrongful practices, such as preferring the Christian religion or going out with unveiled women, have no bearing on the ruling of Al-Misyar marriage or polygyny. Rather, these are major sins or clear apostasy. Polygyny is permissible under the conditions of justice among wives and the ability to fulfill their rights. If the husband says that the Christian religion is better than Islam, this is apostasy and a renunciation of faith, and this entails the annulment of the marriage upon the expiration of the waiting period if he does not return to Islam.