Gemara

(Mishnah): If a man was Mekadesh a woman on condition that she has no vows and she was found to have, she is not Mekudeshes. If he did Nisu'in Stam (without specifying) and she had vows, she leaves without a Kesuvah.

(Rav): If a man was Mekadesh a girl on Tanai and did Nisu'in with her Stam (and the condition was not fulfilled), she needs a Get from him;

(Shmuel): She does not need a Get.

(Abaye): Rav does not assume that he pardoned the condition since he did not mention it at the time of Nisu'in. Rather, a man does not have Bi'as Zenus.

(Seifa): If he did Nisu'in Stam and she had vows, she leaves without a Kesuvah.

Inference: She leaves without a Kesuvah, but she needs a Get.

Suggestion: The case is, he was Mekadesh her on Tanai, and did not mention it at the Nisu'in. This refutes Shmuel!

Rejection: No, in the Seifa he did not stipulate at all. The Reisha means that if he was Mekadesh her on Tanai and did Nisu'in Stam (and she had vows), she is not Mekudeshes;

If he was Mekadesh her Stam and did Nisu'in Stam, and she had vows, she leaves without a Kesuvah.

Inference: She gets no Kesuvah, but she needs a Get.

Question: She does not get a Kesuvah, because he did not want a vowing wife. If so, she should not need a Get either!

Answer #1 (Rabah): She needs a Get only mid'Rabanan.

Answer #2 (Rava): The Tana is unsure whether or not she is Mekudeshes. We are lenient about money (paying a Kesuvah), but we are stringent about Isurim.

(Rabah): Rav and Shmuel argue about a mistake involving one woman like the case of two women (this will be explained). All agree that no Get is needed for a simple mistake involving one woman.

Question (Beraisa): If a Ketanah was married off by her father and divorced from Nisu'in, she is like an orphan in her father's lifetime. If she remarried her ex-husband (and he died childless), all agree that she does Chalitzah but not Yibum, since she was fully divorced but not fully remarried;

This is only if she was widowed before maturity (Na'arus). If she was divorced before maturity and widowed after maturity, whether he remarried her before or after maturity, she may do Chalitzah or Yibum;

R. Eliezer says, she must do Chalitzah.

This is like a mistake about one woman, and Tana'im argue!

Answer: This is not the argument. Rather, the first Tana holds that a man knows that Kidushei Ketanah is not mid'Oraisa. After maturity he intends for Kidushei Bi'ah. R. Eliezer holds that a man thinks that Kidushei Ketanah is mid'Oraisa. He does not intend for Kidushei Bi'ah.

(Rav Acha bar Yakov): If one makes Kidushin on condition and has Bi'ah, all agree that a Get is not required.

(Ula): If one had Bi'ah after Kidushin with a loan, or Kidushin on Tanai, or Kidushin less than a Prutah, all agree that she needs a Get.

(Rav Yosef bar Aba): When the Kidushin was less than a Prutah, all agree that she needs a Get. A person does not err about this. In Ula's other cases a person errs, so a Get is not needed.

(Rav Kahana): If a man was Mekadesh on Tanai and had Bi'ah, she needs a Get;

A case occurred, and Chachamim could not permit her without a Get.

This is unlike the following Tana:

(Rav Yehudah citing R. Yishmael): If "she was not grabbed" she is forbidden. Had she been grabbed, she would be permitted;

In another case she is permitted even if she was not grabbed, i.e. mistaken Kidushin. Even if she has a child, she may do Mi'un and leave her husband.

Rishonim

Rif and Rosh (Kesuvos 34a and 7:11): Rabah taught that Rav and Shmuel argue about a Ta'os involving one woman like the case of two women, i.e. he later had Nisu'in. A simple Ta'os involving one woman is when he was Mekadesh on Tanai and had Bi'ah (i.e. immediately), for then surelyhe did not pardon the Tanai. We conclude unlike Rabah. Rav Kahana obligates a Get in this case. A case occurred, and a Get was required. R. Yishmael allows Mi'un after Kidushei Ta'os, even if there was Bi'ah after maturity. The Halachah does not follow him; Nidah 52a supports this.

Ri'az (in Shiltei ha'Giborim 34a): Even if he said that he has Bi'ah to make Kidushin on Tanai and the Tanai was not fulfilled, she is Mekudeshes. A man does not have Bi'ah for Zenus, rather, for marriage. He stipulated expecting the Tanai to be fulfilled. The Bi'ah of Ishus cannot be annulled.

Rosh: Rashi and Tosfos connote that because a man does not have Bi'as Zenus, there is Vadai Kidushin. If another man was Mekadesh her, we are not concerned. This is reasonable. Kidushei Ketanah mid'Rabanan is not really Bi'as Zenus, yet Rav says that after maturity her husband (Levi) Vadai intends for Kidushin. She does notneed a Get if David was Mekadesh her afterwards. All the more so we say so when Levi was not Mekadesh her before he did Bi'ah! Some say that 'Chachamim could not permit her without a Get' connotes that the Get is due to Safek. Kidushei Ketanah is different, for a man knows that it is nothing (mid'Oraisa) and intends for Kidushei Bi'ah. Regarding a Tanai, he is unsure (perhaps the Tanai was fulfilled), and does not remember to have Bi'ah for Kidushin. Bi'ah for Kidushin is when there are witnesses of seclusion. They are considered to be witnesses of Bi'ah.

Hagahos Ashri (on Rosh 12): Even if he stipulated at the time of Bi'ah, she needs a Get. The Tanai was only regarding the Kesuvah. However, if he explicitly stipulated that it will not be Kidushin unless the Tanai is fulfilled and made a proper Tanai Kaful, if the Tanai was not fulfilled no Get is needed.

Rambam (Hilchos Ishus 7:23): If one was Mekadesh on Tanai and had Nisu'in or Bi'ah with her Stam, she needs a Get from him even if the Tanai was not fulfilled. Perhaps he was Mevatel the Tanai when he had Bi'ah or Nisu'in.

Magid Mishneh: Chachamim required a Get (after Stam Nisu'in) due to Safek. The Rambam explains that Nisu'in is even without Bi'ah.

Poskim

Shulchan Aruch (EH 38:35): If one was Mekadesh on Tanai and had Bi'ah or Nisu'in with her Stam, she needs a Get from him even if the Tanai was not fulfilled. Perhaps he was Mevatel the Tanai when he had Bi'ah or Nisu'in.

Chelkas Mechokek (48): Even if there was Nisu'in without Bi'ah, we say that he pardoned the Tanai, like Ula.

Beis Yosef (DH u'Mah she'Chosav ha'Rambam): Even though Abaye said that Rav and Shmuel argue about whether or not he pardons the Tanai to avoid Bi'as Zenus, Ula says that they argue about Nisu'in without Bi'ah. The Halachah follows Rav. We must say that he pardoned the Tanai. The Rif did not cite Abaye or Ula; he agrees with the Rambam. It sufficed to cite Rabah, who holds that Rav holds that the man pardoned the Tanai.

Question (Beis Yosef 39 DH umi'Kol): In Siman 38, the Tur cited the Rambam to say that even if there was Kenisah (Nisu'in) without Bi'ah, she needs a Get. Why does he say so only about Bi'ah in this Siman?

Answer #1 (Drishah 39:6*): Here the Tur discusses Bi'ah for the Chidush that even after Bi'ah, a Get is needed only due to Safek. However, the Tur connotes that the Chidush is that she needs a Get. According to what I wrote above (38:1), this is not difficult. (Even if Tanai works only for matters possible through a Shali'ach, it works for Bi'ah because we equate all forms of Kidushin. It is a smaller Chidush that Tanai works for Nisu'in, which can be done through a Shali'ach, e.g. handing her over to the husband's Sheluchim.)

Answer #2 (Taz 18): The Rif holds that 'Kenisah' is Bi'ah after a while. It is a bigger Chidush that a Tanai does not inhibit Kidushin even if he had Bi'ah immediately.

Beis Shmuel (59): According to this, we could say that 'Bi'ah' refers to Bi'ah after Chupah, but Bi'ah without Chupah is Bi'as Zenus.

Rema: If she accepted Kidushin from another, she needs a Get from both men.

Chelkas Mechokek (49): We are concerned lest he did not intend for Kidushin because he thought that the Tanai was fulfilled.