The approval of the bride and the wali is needed in all cases, whether it is the first marriage or a subsequent marriage (Fiqh Ahmadiyya, vol 2, p. 39–41).
Explaining the wisdom, Hadrat Musleh Mau‘ud ra wrote:
A difference has been kept between man and woman because a man naturally is less shy in such matters and he himself inquires (about her character), and a woman is shy and her emotions are sensitive, as a result she quickly comes under deception.
(Anwarul ‘Ulum, vol. 8, p. 271; Ahmadiyyat or the True Islam, p. 237)
The requirement of having a wali comes into effect only in the context of marriage, not necessarily in other situations. For example, a woman does not need a wali when making a business deal or any other major decision. They are not any more susceptible to deception than men because in a business environment one is emotionally detached and shyness does not become a factor. Differences in the behavior of men and women are not as distinct. Women do not need a wali in such decisions because emotions and shyness are not a factor in this context.
However, marriage is an entirely different emotional field. Looking for a spouse is a very emotionally involved process where shyness is a natural response. In these overwhelming feelings of shyness, girls are less likely to ask important and direct questions about the suitor that they need to know. Also, in this context of intensified emotions, deceptive men are more likely to take advantage of good-natured women. These differences are practical realities that make a significant difference in the context of searching for a spouse. Hadrat Musleh Mau‘ud ra said:
If this commandment [of wali] is implemented, then many of the deceptions and frauds that are committed against good-natured and trusting women would immediately be removed.
(Anwarul ‘Ulum, vol 8, p. 271; Ahmadiyyat or the True Islam, p. 237).
In another place, her as elaborates:
Islam has given the boy and the girl freedom in marriage, but, it has also placed something marvelous with it, that whether it is a boy or a girl, they should both marry with advice from their parents. If they marry without advice from their parents, then their parents can tell them to divorce, and the son should act accordingly. Thus, boys have been required to seek advice. However, if the parents are insistent, and emphatically stop him without providing any fault or apprehension, then the boy can marry. He is commanded that he should fulfill the desire of his parents as far as possible, but when he thinks that doing so is harmful to him, he is given permission to marry. If a boy marries without seeking advice from his parents, then they can tell him to divorce.
The wisdom in this is that parents look at this relationship from one perspective, and the boy looks at it from another perspective. Beauty, emotions, sexuality, and other matters are in front of the boy, but parents consider the peace and benefit of their son. For this reason, the shari‘ah has ordained that the advice of parents should be sought in this matter so that beneficial matters come before the boy which he may not have been aware of because of his emotions. But if he thinks it beneficial for himself, then he can marry without the consent of his parents as well.
With girls, the shari‘ah has given parents the right of veto. If the girl says that she wishes to marry someone and the parents do not consider it appropriate, then they can deny permission. However, this is a limited right, meaning it can be used twice. If they also deny the third option, then the girl has the right to appeal to qada [court] and claim that her parents are becoming an obstacle in her marriage for their own benefits and purposes. If the judge concurs, then he can give the girl the authority to marry. Then, if she wishes, she can marry the person whom her parents had initially stopped her from marrying.
(Khutbat-e- Mahmud, vol. 3, Khutbat-e-Nikah, p. 252–253)
In another sermon, Hadrat Musleh Mau‘ud ra explains:
The boy must seek the advice of his parents and take it into serious consideration. If he does not seek advice from them at all, then he is at fault. Obviously his parents cannot force him to divorce, but in this case, they have the right to tell him to do so and he should obey them. However, after he has sought their advice, he is free to make his choice as he sees best and no one has the right to compel him.
According to me, such people are ignorant who try to compel someone to marry a certain woman. When the shari‘ah has explained, “marry women of your choice” (4:4), then in every case the choice of the person getting married will be given precedence… Just as men have freedom to marry whoever they wish, so the Holy Quran clearly says that women also have rights in the same way that men have been given rights. Thus, the command “of your choice” is for the man and for the woman.”
(Khutbat-e-Mahmud, vol. 3, Khutbat-e-Nikah, p. 577)
The Holy Prophet sas advised women that:
There is no marriage without the permission of a guardian.
(Sunan Ibn Majah, vol. 3, Book 9, Hadith 1881; Sunan Abi Dawud, Book 11, Hadith 2080; Sunan at-Tirmadhi, vol. 2, Book 6, Hadith 1102).
Similarly, men are taught that they must consult their parents, but after consulting, they are not required to have the consent of their father. The wisdom in these teaching is that a marriage is greater than the couple itself. A bad decision affects the entire family, future generations, and the society at large. Although the person getting married has the final say, the parents are given the right of three vetoes for their daughter, and the right to be part of the decision making process for their son to make sure that the best possible decision is made.