Note to Twelfth Night, 2.4.30, "Let still the woman take / An elder than herself, so wears she to him"

Orsino assumes that wives must adapt themselves to their husbands. (The word "wears" suggests that the wife is the husband's outward adornment, like clothes on a body.) Orsino also assumes that younger people are more adaptable than older ones. Therefore, since it is the wife who must adapt herself to the husband, she needs to be the younger one.

Viola and Orsino
by Walter Howell Deverell