Bashert - is your spouse chosen by G-d?

[Wikipedia] Bashert, (Yiddish: באַשערט), is a Yiddish word that means "destiny". It is often used in the context of one's divinely foreordained spouse or soulmate, who is called "basherte" (female) or "basherter" (male). It can also be used to express the seeming fate or destiny of an auspicious or important event, friendship, or happening.

From the following sources it is apparent that the concept is not clear. In fact someone went to Rav Aharaon Schecter about going ahead with a shidduch based on the fact that she was sure that the boy was her bashert. Rav Aharon responded, "there is no such thing". Obviously he was not disgarding the classic texts - but was simply saying the concept has no significance on a practical level. According to the following sources, even though they present the idea that your spouse is designated in Heaven - there is no guarantee that you will marry that spouse. Even if you do there is no guarantee that you will have a happy and fulfilling marriage. Shalom bayis is not related to marrying your bashert. Consequently it is a concept which should not have any significance either in determining whom to marry or whether to stay marry. If you fall in love with someone - that doesn't mean it is your bashert. If marry and find yourself strongly attracted to someone other than your spouse - it is not because this other person is your "true" bashert. The only significance I can think of is as a compliment or to calm anxiety about getting married.  

Just found this  from Rabbi Rabbi Pruzansky on the OU website

Many years ago, I heard Rav Ahron Soloveichik zt”l explain that bashert (in the Talmud’s language, bat ploni l’ploni) guarantees only one thing: Hashem arranges that you encounter that person. Bashert does not guarantee that you will marry that person, or that the marriage will be a happy and fulfilling one; those depend on our free choice and good middot (character traits). And even what we do after that initial encounter – pursue that person or ignore him/her; look for the good or obsess over flaws – also depends on our bechirah (free choice). As such, it is probably best to remove the bashert issue from our calculations, as it obfuscates instead of clarifies. It should remain in the realm of divine secrets to which we have no access, and which plays no role in our deliberations.

Sotah (2a): When Reish Lakish began talking about the Sotah (suspected adulteress) he asserted that a person only marries a woman according to the nature of his deeds… R’ Yochanon said that it is as difficult to make a couple as splitting the Sea… But this can’t be true since Rav said that 40 days before the creation of an embryo a Heavenly voice (bas kol) proclaims that a particular woman is to marry a particular man, that a particular house and field is to belong to a particular person? The resolution of this contradiction is that the announcement of the bas kol applies to the first marriage while the matching according to deeds refers to the second marriage.

Mo'ed Koton (18b):  Shmuel said that it is permitted to get engaged during Chol HaMoed because if it were required to wait until after the Yom Tov a rival might get engaged to her first… But did Shmuel say that we are worried that another might engage her -  because Shmuel has said that every day a Heavenly voice announces which man will marry which woman?...While it is true that one’s spouse is predetermined but it is possible that a rival will get engaged to her by means of prayer. For example Rava once heard a man praying for a particular woman. Rava told him not to pray in this manner since if she is his predestined wife there is no need to pray for her. However if she is not his predestined than he is going against Providence. Later he overhead him praying that either she should die  or that he should die before she marry another man [he didn’t want to see her marrying another man – Rav Menashe Klein]....Didn’t I tell you not to pray to marry a particular woman? There are proofs to my assertion from Torah, Neviim and Kesuvim that G‑d determines which woman a man should marry. From the Torah: Then Laban and Bethuel answered and said, The thing is from G‑d (Bereishis 24:50). From Neviim: But his [Samson's] father and mother knew not that it was from G‑d (Shoftim 14:4). And from Kesuvim: House and riches are the inheritance of fathers, but a prudent wife is from G‑d (Mishlei 19:14).

Sefer Chasidim (#521): Reuven arranged that Shimon should marry his daughter. However Shimon violated his promise and did not marry her. Even though Reuven’s daughter was embarrassed by this affair Reuven should view that it is for the good. The fact that Shimon married another woman indicates that the second woman was divinely decreed for Shimon. If Shimon had actually married Reuven’s daughter [when she was not intended for him] she would have had to die so that Shimon could marry the other woman. Therefore Reuven should not be upset and fight with Shimon because he broke the engagement. Reuven should not even look depressed since all marriages are determined by G‑d.

Rambam(Teshuva #436): … For example the apparent contradiction to free will represented by the gemora which indicates that one’s spouse is predestined is to be understood as being dependent upon merit. In other words if this man or woman does a mitzva which gives them the merit of having such a spouse—then G‑d arranges that it happen that they marry each other. On the other hand if they so something which merits the punishment of having a marriage without peace and harmony—that will also occur…

Akeidas Yitzchok (#8): [Sotah (2a)] Rabbah bar bar Channa said that matching husband and wife is as difficult as the Splitting of the Sea. In other words just as the Splitting of the Sea is a miracle against the normal pattern of nature in order to reward or punish the actions that man does with free will—so G‑d alters other processes of nature or mazal. Thus a person’s spouse is a reward or punishment that is deserved according to his deeds. No intelligent man has the slightest doubts about this principle. However it seems to be a complete contradiction to the statement of our sages that forty days before the embryo is formed that a Heavenly voice announces who he will marry. How is it conceivable that one’s spouse is determined at time of birth and that no subsequent can improve or worsen the situation? … . However the explanation is that the terms first and second marriage are not meant literally but are referring to two different types of marriage. The first marriage is that which is determined entirely by natural factors and is called first marriage simply because nature precedes deed. However the main marriage is the one that is deserved as a consequence of deeds. It is called here the second marriage because it is the second type of marriage that results from the person’s own behavior and development. Thus we see that marriage is not something which must happen according to predetermination—but man always has free will to do as he chooses…

Ran (Moed Koton 18b):Even though it has been decreed by Heaven which woman a person should marry, it is possible someone else will marry her because his prayers will be accepted. But eventual the wrong person will die or she will be divorced from him and she will marry the proper one

Zohar(1:91b): [Soncino translation] Note that all the figures of souls that are to be born stand before God in pairs, and afterwards when they come to this world God mates them. R. Isaac says: ‘God announces, The daughter of so-and-so for so-and-so.’ R. Jose said: ‘How can that be, seeing that, as the Scripture tells us, “there is nothing new under the sun”?’ R. Judah said: ‘It is true that God creates nothing new under the sun; but this is done above.’ R. Jose further asked: ‘Why is there a proclamation, seeing that, as we have been told by R. Hizkiah in the name of R. Hiya, a man's wife is assigned to him at the very moment when he is born?’ Said R. Abba: ‘Happy are the righteous whose souls are beatified before the Holy King before they come into this world. For we have learnt that when God sends souls into the world they are formed into pairs of male and female, and thus united are placed in the hands of an emissary who has charge of conception, and whose name is Night. After that they are separated, and subsequently taken down among mankind (not always both at the same time). When their time of marriage arrives, God, who knows each spirit and soul, joins them as at first, and proclaims their union. Thus when they are joined they become one body and one soul, right and left in unison, and in this way “there is nothing new under the sun”. You may object that there is also a dictum that “a man only obtains the wife he deserves”. This is so, the meaning being that if he leads a virtuous life he is privileged to marry his own true mate, whose soul emerged at the same time as his.’ R. Hiya asked: ‘Where should a man of good character look for his soul-mate?’ He replied: ‘There is a dictum that a man should sell all his property in order to obtain in marriage a daughter of a scholar, for the special treasure of God is deposited with the learned in the Torah. We have also learnt in the esoteric Mishnah that one whose soul is a second time on earth can through prayer anticipate another in marrying a woman who is really destined for him; this is the meaning of the warning of the colleagues, “it is permissible to affiance a woman on the festival, lest another through prayer anticipate him”; and they were right. The word “another” is used significantly; and it is for this reason that marriages constitute a difficult task for the Almighty, for in all cases “the ways of the Lord are right” (Hos. XIV, 10).’ R. Judah sent a question to R. Eleazar. ‘I know’, he said, ‘about marriages in heaven, but I would like to ask, from where do those whose souls are a second time on earth obtain their mates?’ The reply R. Eleazar sent him was this: ‘It is written: “How shall we do for wives for them that remain?” (Jud. XXI, 7), and again, “and you shall catch every man his wife, etc.” (Ibid. 21). This story of the Benjaminites shows us how it can be done, and hence the dictum “lest another anticipate him through his prayers”Said R. Judah: ‘No wonder we say that marriages constitute a difficult problem for the Almighty! Happy the lot of Israel who learn from the Torah the ways of God and all hidden things, and even the most secret of His mysteries! “The Law of the Lord is perfect”, says the Scripture. Happy the lot of him who occupies himself with the Torah without cessation, for if a man abandons the Torah for one moment, it is as if he abandoned eternal life, as it says, “For it is thy life and the length of thy days” (Deut. XXX, 20), and again, “For length of days and years of life and peace shall they add to thee” (Prov. III, 2).’.