However, we find in the Mishnah earlier that there is a Tana who clearly
disputes the ruling of Rebbi Yehudah ben Beseirah! The Mishnah (107b) states
that if a relative married off the Ketanah without her knowledge or consent
("sh'Lo mi'Da'atah"), the Kidushin does not take effect and she does not
have to do Mi'un.
If the Mishnah agrees with the ruling of Rebbi Yehudah ben Beseirah, then
how are we to understand this Halachah? If the Ketanah's acceptance of
Kidushin from another man constitutes Mi'un and the annulment of her earlier
Kidushin, then it makes no difference whether the first Kidushin was done
with her consent or not -- as soon as she accepts Kidushin from another man,
it is considered as though she did Mi'un and the first Kidushin is annulled!
What difference is there between whether she was married off with her
consent or without her consent? In either case, if she wants to marry
someone else, she may do so and does not need to do Mi''un!
(a) The RAMBAM (Perush ha'Mishnayos) explains the Mishnah there in the most
straightforward sense. When the Ketanah's Kidushin d'Rabanan ("Kidushei
Mi'un") is not valid, she is allowed to marry someone else l'Chatchilah,
The YAM SHEL SHLOMO (13:9) explains that the Rambam holds that Rebbi Yehudah
ben Beseirah's ruling applies only b'Di'eved -- if the Ketanah accepted
Kidushin from someone else, then that annuls her previous marriage.
L'Chatchilah, though, she must first do Mi'un and then afterwards she may
accept Kidushin from someone else. In the case of the Mishnah earlier, when
the Ketanah was married off without her consent, she may marry someone else
even l'Chatchilah and she does not need to do Mi'un. (See MAHARSHA.)
(b) The Rashba cites RABEINU CHANANEL who explains that the Mishnah means
that if she was married off without her consent, then when she grows up and
did not have relations with her husband after she became an adult, she is
allowed to leave him without a Get, and she is not considered to be married
to him. When Kidushin does take effect, such as when she consents it, then
when she becomes an adult she needs a Get if she wants to leave her husband,
even though she did not have relations with him when she was an adult.
However, it seems that this point depends on a Machlokes Amora'im later
(109b). The Amora'im argue whether Kidushei Mi'un automatically turns into
Kidushin d'Oraisa when the girl becomes an adult. Consequently, according to
the opinion that it remains a Kidushin d'Rabanan, there should still be no
difference between being married with Kidushin d'Rabanan with her consent
and being married without her consent; in both cases, she should not need
Mi'un, because accepting Kidushin from the second man annuls the first
(c) The RASHBA himself argues and says that even Kidushei Mi'un that was
done without her consent also requires Mi'un if she wants to marry someone
else. She has the same status as Rebbi Eliezer (in the Seifa of the Mishnah)
gives to every Ketanah who is married with Kidushei Mi'un; even though Rebbi
Eliezer calls her a "Mefutah," he agrees that she needs Mi'un if she wants
to leave him.
When the Mishnah says that it does not need Mi'un, it only means that the
woman is considered a Penuyah (and not married) as far as the husband is
concerned, such as with regard to his right to inherit her, keep the things
that she finds, become Tamei for her and give her Terumah d'Rabanan to eat
(if he is a Kohen).