If Guī Mèi has appeared in your reading, the book is naming a configuration that runs opposite to Jiàn. Where Jiàn is the patient ceremonial marriage entered in proper sequence, Guī Mèi is the younger sister married into a household where she does not hold the first position. The entry is unequal. The book does not tell the reader to avoid it categorically; it tells them not to mistake it for what it is not.

Classical commentary is unsentimental about this hexagram. Some entries are made into positions that are structurally limited from the start — second roles, late entries, unequal partnerships, situations in which one's standing will not match one's contribution. The hexagram appears when the reader is at the threshold of such an entry. The question is not whether the entry is wise in the abstract but whether the reader is making it with the eyes that the configuration requires.

What the book counsels is the doubled attention captured in the image's instruction: 知敝, understand the transient — that is, see that the position is provisional, that what is set will not hold forever, that the dignity available inside it is the dignity of composure rather than command. The reader who enters with these eyes can survive what those who enter believing otherwise cannot.

Guī Mèi's failure mode is the entry made in the belief that it is something other than what it is. The book is firm. The judgment's harsh language — 征凶, 無攸利 — is calibrated to the entry made under illusion. The same entry made under clear sight is a different matter, and the lines of the hexagram make this distinction in detail. The work is to know which entry one is making.