I got married three years ago, and she will not wear the hijab. What is the ruling on that?

The marriage is valid, and you must command your wife to wear the hijab. You should explain to her the Quranic verses that enjoin it, such as Allah’s saying: "O Prophet, tell your wives and your daughters and the women of the believers to bring down over themselves [part] of their outer garments. That is more suitable that they will be known and not be abused. And ever is Allah Forgiving and Merciful" [Al-Ahzab: 59], and His saying: "and to draw their headcovers over their bosoms" [An-Noor: 31], and His saying: "And when you ask [his wives] for something, ask them from behind a partition" [Al-Ahzab: 53].

Scholars have agreed that the hijab is obligatory, differing only regarding the face and hands. The preponderant opinion is that covering them is also obligatory, because the face is the center of beauty and a source of temptation. Therefore, you must command your wife to wear the hijab and use appropriate means to persuade her to do so.