Can a married woman pays for her husband to perform Hajj?
There is nothing wrong with a wife to support her husband financially. Helping each other will bring forth love and affection between them. Allah S.W.T said:
"وتعاونوا على البر والتقوى ولاتعاونوا على الإثم والعدوان"
Which means: "And help each other in goodness, and do not help each other in matters of sin and infringement." (Al-Maidah: 2)
In fact, it is an act of worship, especially if the donated money is used by her husband to perform worship.
Hajj is not an obligation for those who can not afford or unable to perform it. However, if a person receives a gift money, or a charity, from his wife or other person, then it is not wrong for him to perform the hajj with the money.