I am a girl married to a man who before the marriage contract led me to believe that he was not going to marry more than one wife. Since the marriage contract, he may marry again. Now I'm upset. What do you advise me to do?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If you have stipulated on your husband before establishing your marriage contract that he should not marry another woman, you may demand that he fulfills that condition pursuant to the saying of the Prophet : “From among all the conditions which you have to fulfill, the conditions which legalize for you to have sexual relations (i.e. the marriage contract) have the greatest right to be fulfilled.” [Al-Bukhari and Muslim]

If you have not stipulated such a condition at the time of marriage, then you can only demand that he treats you justly and the other wife has every right to what Allah permitted the husband towards his wife. Allah Says Allah Says (what means): {… then marry (other) women of your choice, two or three, or four;…} [Quran 4:3]

Allah knows best.