DEAR MISS MANNERS: I am 14 years old. As you may know, many people my age (including myself) have joined the popular social networking sites.

I had planned a sleepover with a friend of mine, not someone I see at school every day. I do not go to the site often, but that evening I was waiting for her to arrive and I went online. I then saw that a few days ago she had sent me a message there, telling me that she could no longer come to my sleepover.

I found this very rude. What if I had not checked my account at that time? I could have just sat there for an hour like a silly goose and not have known that she canceled. Wouldn't the right thing to do have been for her to at least call me? Please address this, what I think was a very unmannerly, horrible incident.

GENTLE READER: Yes, and Miss Manners is even less casual than you are about a guest's canceling an invitation once accepted.

But assuming that you find your friend's reasons compelling, let us deal with the manner in which she did so. Someone who mails you a conventional letter at an address that you have supplied can reasonably expect that you will receive it. This is true even today, when modern technology provides a plethora of ways to receive correspondence without supplying additional eyes and ears with which to process it.

But when canceling an invitation, there is a special burden on the ex-guest to see that the message is received. When your friend did not hear from you on the social network site, she should have proceeded through other forms of communication until she made contact.

DEAR MISS MANNERS: I am currently divorced. My ex-wife just got married to a woman. For the longest time, I was playing the field, and now I have a girlfriend.

I am quite cordial with my ex and want to introduce her new spouse to my new girlfriend. How should I address her spouse?

GENTLE READER: Both ladies have names, Miss Manners supposes. And both have had ample opportunity to learn the various relationships involved, so you need only introduce them by name.

When introducing either to others, it would actually be the simpler to say "my former wife and her wife," with their names, and simply the name of your friend, rather than dealing with the awkward question of whether your friend is a girlfriend, partner, or whichever term you find least awkward.

DEAR MISS MANNERS: I take taxis to the airport about four or five times per year. Most drivers take the direct route, but a fair number will take a slightly longer route to up the fare.

What is the proper etiquette for what to do when this happens? Skip the tip? Argue over the bill? Pretend nothing happened?

GENTLE READER: None of the above. Miss Manners urges you to speak up -- and quickly. Specify your preferred route when you give your destination. This will forestall any contemplated dishonesty -- and you may even learn that the driver was actually trying to save you money by avoiding a delay of which you were unaware.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Universal Uclick, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: My good friend is obsessed with how expensive things are. She likes to share about her expensive, top-of-the-line jewelry, brand-new car, new house, luxurious vacations, large income tax refund and so on. She insists it's not bragging, as she is proud -- of her husband.

This is all paid for with what her husband makes and gives to her generously. She got mad at me once because I thanked her husband, but not her, for a dinner that he treated us to. She said it's her money, too. (She is unemployed and is a stay-at-home mom.)

I told her that when I go out with my parents, I thank my dad when he pulls out his credit card, not my mom. (I also thank my friends' husbands when they pay.) Nor does my mom care, or other wives that I know of. They have jobs and have shared credit cards, but he was the one with the card out, so it's an automatic thank-you to the person with a card.

How do I get this friend to stop obsessing and realize how she sounds when she is bragging about how expensive something is?

She has accused me of being jealous because I am not well off. But honestly, I have -- or had -- exactly the same income as her, minus the husband to pay off all her bills, or their house.

Even the husband complains how much he does for her, and she did not give him a Christmas present. I tell him that's his problem and he needs to address his issues with her. But as long as he enjoys spoiling her without expecting anything in return, that's his pattern in their relationship.

How do I tell him, too, that his spoiling her with the finest things is turning her into a princess who can't stop obsessing over how much things are? She gets angry very quickly, and I'm afraid I don't know how to bring it up to her that I don't care how much "they" made in tax returns. I get it and assume how luxurious her vacations are. I don't need her telling me the price tag.

GENTLE READER: Why do you need her at all? You describe this good friendship as being a constant round of bickering and bragging on one side, and interfering and nagging on the other side -- yours.

However, Miss Manners has learned that people who complain about impossible conditions while continuing to contribute to them may not be seeking change. The situation, such as it is, seems to work, and they are just venting.

This seems to be equally true of your friend's marriage, and of your friendship with her.

DEAR MISS MANNERS: Due to their similarity, can a butter knife be passed off as a fish knife in a formal setting (where there should be no butter knife present to reveal the ruse)?

GENTLE READER: If it is one of those notched butter servers, sure. Miss Manners promises not to tell.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Universal Uclick, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: I wrote a thank-you note to a co-worker over a year and half ago, and just this week it came back with a sticky note attached that said, "I am returning this card to you with the spirit in which it was given."

What does this mean? Is it a true thank-you, or a slap in the face? I am confused; I have never gotten a thank-you note back, and she held on to it for almost two years.

GENTLE READER: Nothing good can come from sentiments exchanged on sticky notes. Evidently, this person thought that your thank-you note was somehow sarcastic and has decided to take it as an insult.

Miss Manners suggests that you ignore it. If you still work with the writer and your curiosity gets the better of you, you may ask if you inadvertently offended her. But if the answer is yes, please resist the urge to write, "I'm sorry" on yet another sticky note.

DEAR MISS MANNERS: I will be moving far away soon, and I would like a way to show my friends how much I will miss them and how greatly I have appreciated having them in my life.

Would it be in poor taste for me to throw a going-away party for myself? Would there be a more appropriate way of naming such an event, since my goal is to celebrate the guests, even though I am the one leaving? I feel like it would be rude to hint to others that I want a party, but it does not seem quite polite to simply throw one myself. GENTLE READER: One doesn't have to name the occasion in order to host a party. That you wish to see your friends before you leave is reason enough.

Unfortunately, Miss Manners has found that in the current climate, making a party into an "event" makes people suspect that presents are somehow required. Simply invite your friends to a party, and if asked about the occasion, say, "I wanted to see everyone one more time before I moved."

DEAR MISS MANNERS: For a few months, I received voice lessons from a lovely and talented tutor. However, I had to quit taking lessons because of scheduling conflicts.

Now, a year and a half later, I'm having some pangs of remorse. I really admired my tutor, but I never gave a reason for my failure to return.

I'm wondering, is it too late for me to write her a note, thanking her for what she taught me and explaining why I couldn't come back? Or do you think that after so long, it is inconsequential?

GENTLE READER: It would be lovely to send a note apologizing for discontinuing the lessons, especially if the transaction was abrupt. Briefly explain that your schedule prevented you from continuing.

Miss Manners notes that this was a business transaction, so social etiquette is not strictly required. But it is certainly never remiss to be thankful and polite, especially if you want to regain this person's trust in scheduling with you in the future.

(Please send your questions to Miss Manners at her website, www.missmanners.com; to her email, dearmissmanners@gmail.com; or through postal mail to Miss Manners, Universal Uclick, 1130 Walnut St., Kansas City, MO 64106.)