DEAR MISS MANNERS - My ex-husband and I have each been invited to a large affair given by mutual friends.

The hostess informed me that she was only allowing those single people who have been involved in a "long-term relationship" to bring an escort. Although I have been seeing someone for several months, she told me I did not fit into this category. She conveniently failed to mention that my ex-husband did. (I found this out on my own.)It will be humiliating attending this affair unescorted, while my ex is with his girlfriend. The hostess knows how uncomfortable I am around him, and I am hurt that she would be so insensitive as to put me in this position.

There will be very few unescorted single people invited, and I feel that she should have at least allowed us the option of bringing an escort.

GENTLE READER - Permit Miss Manners a moment of sympathy with your hostess before she takes up your case. Time was when people were allowed to decide who their guests would be. Permanent (it was thought) attachments, which is to say marriages and engagements, were recognized in invitations, but transient ones were not.

Today, who can tell which is what? Yet if the hostess asks everyone to bring someone, half her guests may be strangers to her. Your friend has merely tried to get back to welcoming only serious additions to her circle.

Nevertheless, there are always hardship circumstances to be considered - that is why we have courts of etiquette, and you are appealing to her now - and Miss Manners agrees that an exception should have been made for your particular situation.

DEAR MISS MANNERS - When I encounter the manners of Japanese friends, I feel like an Ugly American in my own country.

For example, I found out that Japanese courtesy requires that an invitation be declined three times before being accepted. I think I damaged my friendship with a Japanese woman, who is living here temporarily, by jumping at her gracious invitations and never persuading her to accept mine.

Also, my Japanese friends find ways to give me presents when they visit me. The timing and selection of these gifts are mysteries to me.

Should I continue in my uncouth Western ways or try to reciprocate in kind? How about when I visit people in Japan (in-laws and friends)?

GENTLE READER - It is not only because she is a pedant that Miss Manners reminds you that the title character of "The Ugly American" was a wonderful man who only sought to help the foreigners among whom he lived. The nickname inspired by his appearance has been used ever since to describe Americans who behave arrogantly overseas, which is the opposite of what he did.

Miss Manners' point is that one need not be ashamed of American behavior, which, at its best, is free, generous and dignified. Japanese manners are more elaborate than American, but Miss Manners does not concede that they (still less aristocratic European manners, which too many Americans admire excessively) are better.

In any case, this is not a contest. Your Japanese friends and in-laws know there is a cultural difference and they should be as interested in understanding our manners as you in understanding theirs.

The manners of the country one is in generally prevail, although people from neither country will be able to mimic the other country's behavior perfectly. An attempt to learn what is proper, including asking questions, is considered sufficient evidence of good will.

Incidentally, Miss Manners is counting on you tactfully to tell your friend here, before she finds herself in social isolation, that urging invitations after they have been declined is considered intrusive in America, and quick acceptance is flattering.

DEAR MISS MANNERS - Having just landed a new job, my father called me and said he would be flying through on a business trip. I invited him for dinner, but he could not tell me which day he would be here. He said he would call the next day. He did not.

Two days later, he called and said he was in town and would like to come that evening. I said, "Sure." Then he said, "How about if I bring my boss - he's sitting right here?" I asked if it was necessary and he said, "Sure is - we'll be there at 5:30."

I packed up the kids and flew to the grocery store to get more food. When he arrived, he was alone and said his boss decided not to come.

Would it have been improper to throw the extra food at him?

GENTLE READER - We don't throw food at Daddy, even when he has behaved badly. Sorry.

However, we do say, in an affectionate tone: "Daddy, for heaven's sake. I love to have you here, but give me a little warning, so I can plan. Here I tried to do you proud in front of your boss, with no notice or choice about the matter, and nothing came of it."

In a dilemma about giving or receiving presents? Help is available in Miss Manners' "Present-Giving" pamphlet. Send $1.50 to Miss Manners, in care of the Deseret News, P.O. Box 91428, Cleveland, OH 44101-3428.

Feeling incorrect? Address your etiquette questions (in black or blue-black ink on white writing paper) to Miss Manners, in care of the Deseret News, P.O. Box 1257, Salt Lake City, UT 84110. The quill shortage prevents Miss Manners from answering questions other than through this column.