פירוש על יבמות 13:4

A ketana [girl less than 12 years and a day old] who does not have a father, or she has a father but her father had married her off and she became a widow or she was divorced while still a ketana, and thus she becomes like an orphan in her father's lifetime for he has no authority over her anymore, and she is married off with her permission, since her marriage is only on a rabbinical level, if she does not like her husband, she does not need a get [bill of divorce] from him, but rather she can leave through [the law of] me'un [where she can simply denounce the marriage]. But if she was married off without her permission, or even if it was with her permission, but she didn't know to keep her marriage, she doesn't even need me'un. Rem"a: Ideally the court should make sure not to allow the marriage of an orphan ketana when it seems it will end in me'un. And we can only judge this according to what we can see (Hagahot Maimoni perek 11 in the name of R"Y).