Why doesn't a man mourn his wife for four months and ten days, just as a woman mourns her husband? What is the wisdom behind this, and is this considered an injustice to women and their rights?

Allah Almighty is Wise and All-Knowing, and the proofs of His wisdom and knowledge are countless. An example of this is the human heart and its wonders. Allah established the heavens and the earth upon truth and justice, and He forbade injustice upon Himself and made it forbidden among His servants. Allah Almighty says: "Indeed, Allah does not wrong [even] an atom's weight," and He says: "Indeed, Allah does not wrong the people at all, but it is the people who wrong themselves." And in the Hadith Qudsi: "O My servants, I have forbidden injustice for Myself and made it forbidden among you, so do not oppress one another."

From the wisdom of commanding a woman to observe mourning (haddad) for her husband is that the 'iddah (waiting period) clarifies the purity of the womb from pregnancy, and due to the immense right of the husband over her, and mourning is a follow-up to the 'iddah. During the 'iddah, it is impermissible for a woman to marry or be proposed to. Beautification and adornment are forbidden because they lead to her coveting and men coveting her. Once the 'iddah ends, it becomes permissible for her to be proposed to by those who desire to marry her.