Husband Rights
This is a matter of mutual love and mutual respect. As far as Islam is concerned, there is no obligation on a woman to cover her face with Niqab hence there is no sin if a woman is not doing it. But if a wife chooses to do this for her husband, then it is a commendable act. Following video might also prove helpful in this regard: Please refer to the video below from 1:28:21 to 1:31:05 https://youtu.be/hzSwD2Nq5gg?t=5301