When Is Disinviting a Party Guest Okay?

Q. My husband and I were invited (and RSVP’d yes) to an annual dinner party that we've attended in the past. He was unable to attend at the last minute, so I called the hostess to let her know. She apologized but said I couldn’t attend without him because it was a “couples only” party. These requirements were never mentioned on the initial invitation. I am shocked. Is it proper etiquette to uninvite a guest under these circumstances?
Michelle Bean
Temecula, California
 
A. Picture me, with my hands to my face, doing Edvard Munch’s The Scream and you will understand that my answer is: No! While there are certainly all kinds of mores about crafting a guest list for a dinner party, the one rule that is nonnegotiable is that you cannot disinvite someone from a party of any kind, for any reason, once he or she has been invited. Sure, there have been situations where we’ve all wished we could disinvite certain people―you can’t stand one guest’s husband, another wants to bring a friend―but you just can’t. And your story provides the perfect illustration of why: Your hostess friend was so concerned about maintaining a perfectly balanced, couples-only party that she was willing to risk insulting you and jeopardizing your friendship. What party is worth that?
 
—Julie Rottenberg