The halacha as I understand it is that only the man can take the final decision on divorce. I hear there are workarounds, but conceptually - why is that so?
Why can't a woman decide by herself to divorce?
Someone asked in the office, I had no answer.
The woman can ask but the torah specifies that the man must write (order the writing of) the divorce document and deliver it to her. There are cases in which the court can order the man to write the get, but he must be the one to write it (or order it written) and it must be of his own free will. This is similar to the rules of getting married in which the man must give the woman the ring (or other object) in order for the wedding to be valid.
Rav Hirsch points out that the methodology of a divorce must be similar to the methodology of the marriage. Just as the man must give the wife an object and "take" her into his house, similarly he must be the one to sever that relationship.
The first act קידושין ... is the personal adoption of the wife by the husband. ... and is further explained in Kidushin 2a, this adoption is made in the form of an act of appropriation
... the complete unity of the wife with the person of her husband is not yet completed, but is conditional on another act ... chupah
This means that just as the Bnei Yisrael at Har Sinai gave themselves up to the authority of the Torah, the woman has given up her authority to separate from the husband and the marriage can only be ended by death and divorce.
All of these laws can be summarised in one idea: the written word is to be used in the place of the spoken one, instead of a speech made with full considered conscious intention, the thought of divorce must be expressed in writing with equal import of its import and intention., ...
... By depositing the deed of divorce in any place that is her domain ... the husband gives up any rights he has in it ...
Further Rav Hirsch points out
ושלחה מביתו is simply the expression used here for the legal effect of the act of divorce: the freeing of the marriage bond which hitherto was in force, and the releasing of the belonging to the husband
This is exactly the inverse of the sealing of the original marriage bond.
Rav Hirsch also points out it was after more than two thousand years that there was on the whole no abuse of that authority and it was not "progress" that it was found necessary to curtail that authority to protect the woman. He then refers to an article that he wrote on the Position of Jewish Women. See the article in volume 2 of "Judaism Eternal".
This means that the woman cannot "decide on her own" to divorce. Even in cases in which the woman can go to bais din to force the husband to grand a divorce, the husband must still write and deliver the get. The technical methodology requires that the initiative come from the husband.
As an example, we see the Rambam. Note that this does not say that the halacha of maus is accepted by everyone. I am giving it to show that even in this case, the technical requirement still applies.
The Rambam Hilchos Ishus 14:8 points out that a woman can force the divorce to occur by acting in such a way as to be in the status of "moredes", that is, a rebellious wife, such as taking a vow to have no relations with the husband. In that case, the husband must divorce her, though she does not receive the kesuvah. However, the technical methodology requires that the initiative come from the husband.
A woman who withholds marital intimacy from her husband is called a moredet ("a rebel"). She is asked why she has rebelled. If she answers: "Because I am repulsed by him and I cannot voluntarily engage in relations with him," her husband should be compelled to divorce her immediately. For she is not like a captive, [to be forced] to engage in relations with one she loathes.14
[In such an instance, as part of] the divorce [settlement], she does not receive any of the money promised her in her ketubah.15
Note that Rambam Hilchos Gerushin 2:20states that the court can order the man coerced until he says "I am doing this of my own free will" because of the principle that any Jew wants to obey the Torah. However, if he does not say this, the divorce is invalid.
When a man whom the law requires to be compelled to divorce his wife51 does not desire to divorce her, the court should have him beaten until he consents, at which time they should have a get written. The get is acceptable. This applies at all times and in all places.52
Similarly, if gentiles beat him while telling him: "Do what the Jews are telling you to do," and the Jews have the gentiles apply pressure on him until [he consents] to divorce his wife, the divorce is acceptable. If, however, the gentiles compel him to write [a get] on their own initiative, the get is [merely] unacceptable.53The rationale is that the law requires him to give a divorce.
Why is this get not void? For he is being compelled - either by Jews or by gentiles - [to divorce] against his will [and a get must be given voluntarily].
Because the concept of being compelled against one's will applies only when speaking about a person who is being compelled and forced to do something that the Torah does not obligate him to do - e.g., a person who was beaten until he consented to a sale,54 or to give a present. If, however, a person's evil inclination presses him to negate [the observance of] a mitzvah or to commit a transgression, and he was beaten until he performed the action he was obligated to perform, or he dissociated himself from the forbidden action, he is not considered to have been forced against his will. On the contrary, it is he himself who is forcing [his own conduct to become debased].55
With regard to this person who [outwardly] refuses to divorce [his wife] - he wants to be part of the Jewish people, and he wants to perform all the mitzvot and eschew all the transgressions; it is only his evil inclination that presses him. Therefore, when he is beaten until his [evil] inclination has been weakened, and he consents [to the divorce], he is considered to have performed the divorce willfully.
Your question uses some ambiguous language. You asked "Why can't a woman decide by herself to divorce?" The answer to your question depends on what you mean by "can't."
On a simple level, the Torah lays out the procedure for divorce. Part of that procedure is the husband writing a bill of divorce (called a get) and giving it to the wife. When we understand that this is the procedure for divorce, it becomes obvious why it is impossible for a woman to decide on her own to get a divorce: the necessary steps to achieve divorce are not all within her own power. Her husband must comply to some extent. According to one interpretation of your question, the above is the answer.
On the other hand, you might be asking one step further: "Why does the procedure for divorce require a step that is outside of the power of the wife to effect?" This question is not so easily answered. God doesn't tell us the reason for the vast majority of the mitzvot in the Torah.
It should be noted that there are cases where a woman can demand and a beit din can compel the man to divorce his wife. According to this article on Chabad.org, these cases include neglect of basic marital needs, physical and/or emotional abuse, unbearable circumstances, childlessness, refusal to make aliya if she wants to, and refusal to engage in marital relations. As I mentioned above, the husband still must produce a get for the divorce to take effect; however, in any of these cases, failure to do so is a violation of halakha. A beit din may even impose corporal punishment on the man until he divorces his wife.
A woman can't ask for a divorce because the stipulations in the Torah, and the halacha do not grant her the power to ask for a divorce. For more details on that, read everyone else's answers.
However, women were given the power to initiate divorce during the time of the Geonim. During the time of the Geonim, women were granted the power to initiate divorce by having a divorce clause inserted into the kethubbah. This may sound strange to Ashkenazim as their kethubboth have been a fixed text for nearly a millenia. But in the times of the Talmud, until this very day, Mizrahi Jewish communities have a custom of drafting kethubboth unique to their marriage, stipulating things down to the smallest details. One such clause that was in use during the time of the Geonim was one that allowed women to initiate divorce, and therefore forfeiting her kethubbah money. Here is a complete divorce clause that was brought to light in the Cairo Genizah:
...And if this Maliha [the bride] hates this Sa`id, her husband, and desires to leave his home, she shall lose her ketubbah money, and she shall not take anything except that which she brought in from the house of her father alone; and she shall go out by the authorization of the court and with the consent of our masters, the sages...”
Source: Jewish marriage in Palestine : a Cairo Genizah Study
The witnesses of these Kethubboth were often high ranking scribes and Rabbis of the time, which shows they were not fringe occurrences. This clause allowed the women to sidestep the requirement of receiving permission of her husband, or requiring him to give her a get. She would go to the beit din, and have them dissolve the marriage, without needing anything from the husband. Giving her equal power in dissolving a marriage.
So the more complete answer to your question is as follows: women cannot initiate divorce because we as a community have decided not to allow them to do so, and when discoveries like the above kethubboth are found, we suppress them, rather than bring them back into common usage to solve problems like agunoth. A problem we historically already had an answer for.
Maybe the simple reason is that for the husband to have stability (and a man will take care of somthing/someone that is his, that can not be taken away much better then somthing that can leave)
Marrige is not what it seems now (a new idea maybe less then 100 years) to the western world
In short, the answer is because this is what G-d Almighty told us.
Marriage is an old thing.
It was given to us by G-d, and it starts by the husband offering it to his wife and she willfully accepts (if she was forced it is invalid) and it ends when he gives something to his wife and she accepts.
See Mishneh Torah» Sefer Nashim » Gerushin - Chapter One
Halacha 2
What are the sources that indicate that these ten requirements stem from Scripture itself? [They are derived from Deuteronomy 24:1, which] states: "And if it comes to pass that she does not find favor in his eyes, and he will write a bill of divorce for her, place it in her hand and send her from his home.".
"If... she does not find favor in his eyes" - this indicates that he divorces her only on his own initiative. If a woman is divorced against her husband's will, the divorce is invalid. A woman may, however, be divorced either voluntarily or against her will. (Biblically speaking)
Halacha 3
"And he will write" - this teaches that a woman can be divorced only by means of a written document.
"For her" - that it should be written for her sake.
"A bill of divorce" - i.e., a deed that severs the relationship between [the husband and his wife], without leaving him any jurisdiction over her. If [the relationship] between them is not entirely severed, the divorce is not effective, as will be explained...
Sorry, I will be very frank.
The man take a wife for himself (and no one else can use her).
He can let her free.
Similarly, in the Russian language until today the man gets married and the woman does not (she goes for the husband)
An inexact analogy will be (the gemoro menachot 43b on bottom,
And is not that (a slave) the same as a woman? ( rashi explains this question either 1 a woman is a maidservant to her husband is as a slave to his master or 2 For with regard to the performance of precepts a woman and a slave are on the same footing;)(answer:) A slave is more contemptible.
(R' Moshe Feinstein sais that if it was not rashi he would say it is wrong, since when looking at all of the wife's rights, it is the husband who is the slave to his wife! (biblically the husband only has one right over his wife and that is to use her (intimacy))).
a slave, a slave belonging to a jew has a lot of rights but can not let himself free, only the master can let him free,
G-d almighty took/chose the Jews, the Jews exepted now they can not turn away
The condition that only he can divorce her was one of the conditions that she agreed to him to marry her.
Why do you think that the woman should have the right to devorce?
@vaxquis below brings a good point "since a woman brings the child and takes care of raising it, the man has to take care of her. Since it's he who is the caretaker and she is the one who is taken care of, she can't apply for divorce the same way a tree can't uproot itself. She can leave, she can kill the husband, she can do a lot of things, she can act - but should that imply it would be according to the G-d's law? If you're a true Jew, you respect the tradition. If you don't want to respect that tradition, nobody forces you to be a Jew"
@DoubleAA probably wants me to add some of the obligations of a husband to his wife
Similarly, our Sages commanded that man honor his wife more than his own person, and love her as he loves his own person. If he has financial resources, he should offer her benefits in accordance with his resources. He should not cast a superfluous measure of fear over her. He should talk with her gently, being neither sad nor angry.
1) Maybe because the Tora tends to strengthen the jewish marriage and reduce divorce rate. A recent survey cited in Wikipedia showed that (in the UK),
93% of divorce cases were petitioned by wives
Probably, man is more stable than woman, and attaches himself to his wife more strongly than she. Not necessarily in terms of intensity, but of constancy over time.
2) If the woman has right to demand divorce (for example when the husband does not fullfill his marital obligations), the rabbinical court can make pressure on him, even by hitting him, until he accepts.
