אבן העזר ל״גEven HaEzer 33

Se’if 1א׳

בְּבִיאָה כֵּיצַד, אָמַר לָהּ בִּפְנֵי שְׁנֵי עֵדִים: "הֲרֵי אַתְּ מְקֻדֶּשֶׁת לִי בְּבִיאָה זוֹ", וְנִתְיַחֵד עִמָּהּ בִּפְנֵיהֶם, הֲרֵי זוֹ מְקֻדֶּשֶׁת (אַף עַל גַּב דְּחֻצְפָּא הִיא). בֵּין שֶׁבָּא עָלֶיהָ כְּדַרְכָּהּ בֵּין שֶׁלֹּא כְּדַרְכָּהּ (טוּר). וְאֵין דִּינָהּ אֶלָּא כִּמְאֹרָסָה, וְלֹא כִּנְשׂוּאָה. הַגָּה: וְיֵשׁ אוֹמְרִים דַּוְקָא שֶׁבָּא עָלֶיהָ בְּבֵית חָמִיו, אֲבָל כְּנָּסָהּ לְבֵיתוֹ וּבָא עָלֶיהָ, אוֹ שֶׁקִּדְּשָׁה כְּבָר וּבָא עָלֶיהָ, דִּינָהּ כִּנְשׂוּאָה. יֵשׁ אוֹמְרִים דְּפָנוּי הַבָּא עַל הַפְּנוּיָה לִפְנֵי עֵדִים, חוֹשְׁשִׁין שֶׁמָּא כִּוֵּן לְשֵׁם קִדּוּשִׁין (מָרְדְּכַי פֶּרֶק הָאוֹמֵר), דַּחֲזָקָה אֵין אָדָם עוֹשֶׂה בְּעִילָתוֹ בְּעִילַת זְנוּת. אֲבָל אִם כְּבָר הֻחְזַק לִזְנוּת, אוֹ שֶׁיֵּשׁ לוֹ אִשָּׁה אַחֶרֶת, לָא חַיְשִׁינָן (תְּרוּמַת הַדֶּשֶׁן סִימָן ר"ט). וְיֵשׁ מְקִלִּין בְּכָל עִנְיָן, וְעַיֵּן לְקַמָּן סִימָן קמ"ט וְקנ"ו סָעִיף ב', וּלְעֵיל סִימָן ט"ו סָעִיף יוּ"ד:

With sex, how? He said to her before two witnesses: "Behold you are married to me with this sex," and he secludes himself with her before two witnesses, behold she is betrothed (even though she is bold.) Either he has sex with her in the normative fashion or he has sex with her in the non-normative fashion. And her status is only as someone who is engaged, not like a married woman. Ram"a: There are those who say that it is precisely when he has sex with her in the house of his father-in-law, but if he brought her into his own house and had sex with her, or betrothed her already and had sex with her, she is considered like a married woman. There are those who say that a single man who has sex with a single woman before witnesses, we suspect that he intends [this act] for the sake of marriage, and the presumption is that a man does not have promiscuous sex. But if he is already presumed towards promiscuity, or that he has another wife, we are not concerned. There are those who are lenient in this matter.

Se’if 2ב׳

הַמְקַדֵּשׁ בְּבִיאָה, דַּעְתּוֹ עַל גְּמַר בִּיאָה. לְפִיכָךְ, אִם קֹדֶם שֶׁגָּמַר קִבְּלָה קִדּוּשִׁין מֵאַחֵר, מְקֻדֶּשֶׁת לַשֵּׁנִי. אֲבָל אִם הֶעֱרָה בָּהּ וּפֵרַשׁ מִיָּד, אוֹ שֶׁאָמַר תְּחִלָּה שֶׁדַּעְתּוֹ לִקְנוֹת בְּהַעֲרָאָה, קָנָה מִיָּד:

The one who marries a woman with sex, his intention [is fulfilled] upon finishing the sexual act. Therefore, if before he finished she received kiddushin from another, she is married to the second [person]. But if he was stimulated in her, and leaves immediately, or when he said before that his intention to acquire upon being stimulated, he acquires immediately.