"Couples who don't fight couldn't have much of a relationship," a lady announced at dinner, and all the nearby guests turned automatically to look at her husband, who was obliviously out of earshot, blamelessly chewing his chicken.

"It's healthy to have a good knockdown, drag-out fight every once in a while," she persisted. "It makes for a good marriage -- it clears the air."

Her listeners, whose faces had all returned in her direction, tennis-fan style, reverted to him, in expectation of what he might hurtle through the air in order to clear it.

But no plates came sailing across the table. Apparently the happy couple were not going to illustrate their formula for a successful marriage. The guests turned to their own plates.

Unsolicited information about how life should best be lived is so generously distributed these days that no one remarked on this revelation. Sudden, involuntary insights into the intimate lives of acquaintances aren't that startling any more. There was the merest polite pause before the conversation shifted to something more riveting, such as that perennial favorite, the difficulty of getting good service on airlines. (Traditionally, the topic was the difficulty of getting good servants, but the idea is the same.)

But Miss Manners, for one, was sorry to see the matter dropped without a fight, as it were. It seemed to her simply the perpetuation of another truism offering dangerous comfort to those who believe in therapeutic rudeness.

Why should fighting be good for marriage, or any other intimate relationship (as one feels obliged to add these days)?

Is bashing really that much more fun than making nice?

Miss Manners agrees that it would be odd for a couple to agree on everything. Not unhealthy, just odd. She doesn't even concede that it would be boring, there being quite a cozy comfort in tsk-tsking with a companion, from the shared smugness of agreements about how awful the rest of the world is. Absence of strife is not a major problem in most modern lives.

But the fondest of couples may disagree politely. Those who advocate fighting seem to believe that the only alternative to it is tyranny and acquiescence, accompanied by contempt and resentment.

Miss Manners has always believed that the home, far from being the place where one can be freely and comfortably rude, is the place where one ought to be most protected from rudeness. The rules of airing marital disagreements therefore require even more delicacy and politeness than do conflicts between those with less at stake emotionally.

One starts with a ban on unpleasant forms of expressing displeasure: Raising the voice, cursing, door-slamming and abusing property should, of course, be as thoroughly outlawed as hitting. So should the hurtful use of privileged information confided under happier circumstances.

The word for "wrong," when used to describe the other's beliefs, factual accounts, attitudes or practices, is "mistaken." Trespasses can only be announced after the phrase, "I'm sure you didn't mean to, but ..."

In a proper marital dispute, issues are resolved by whoever is more strongly affected by them, rather than by recourse to anything resembling an outside standard. That you drive me crazy by humming tunelessly is more important than the fact that you have a right to do so, for example.

And the victor always absolves the conceder from blame. If an all-purpose "It wasn't your fault" isn't enough, he or she must supply the excuse: "I should have seen that you were exhausted" or "It's the strange weather -- it's driving us all crazy" or whatever will pass.

Miss Manners promises that it is as possible to have a satisfying conflict under these rules as under the more pugnacious ones believers in therapeutic rudeness often condone.

What is more, it is an excellent achievement to be insufferable about when there are children, who are naturally interested in engaging in good, healthy, destructive, unbearable fights among themselves.

"I don't care who did what -- yelling is not permitted in this house," parents who have learned restraint are entitled to say. "You are not allowed to slam doors." And then, of course, they can graciously tell each other: "I know you didn't mean it, dear. It's the children being impossible that's getting to you."

A friend took me to lunch, and we ordered the same entree. She liked it; I simply did not. Since it was not the fault of the restaurant, I felt I had no right to ask for something else (at my own expense, of course). I ate most of it, but I really did not enjoy it.

Could I properly have done anything else? What if one is dining alone in that situation?

If you are dining alone, you may buy 12 dishes, if you like, and leave them all untouched. You will probably have a difficult time assuring the staff that everything really is all right, but provided you do not attempt to blame the restaurant for your changes of mind, you will not have committed an error of etiquette.

The situation is quite different when you are someone's guest and she feels responsible for your enjoyment. You cannot decently say, "I don't like the dinner you bought me, so I'll buy one myself."

Just eat it, will you? How you behave is more important than what you eat.

Anyway, how bad can food be, when it is of your own choice and you acknowledge it to be properly cooked?

If you are gracious, perhaps your friend will want to invite you out again, and then you can order something different.