DEAR MISS MANNERS: My wife and I have a successful marriage and two grown children. We love each other very much.

My problem is her obsession with social media and all of the goings-on with her friends. She constantly asks me to look at pictures, videos, events and the minutiae from her online friends.

In the beginning, I used to take time to look, but now I can’t stand looking at another baby video, or another post from a friend attending a polo match. This stuff is so uninteresting to me. These people are not really her friends. They may have been childhood friends 50 years ago, or worked together 30 years ago. I have no clue who they are.

I have tried to tell her nicely multiple times that these things do not interest me, but she gets peeved and generally testy when I decline.

Then there are times when I will relate a story about my day, and she will claim “not to be interested” because I cannot show interest in her “world.”

Social media is ruining our society. In general, we have become a world of “Look at me, I’m here,” and “Look at me, I’m doing such and such.” How do I handle this?

GENTLE READER: Having attended quite a few children’s birthday parties in her time, Miss Manners is used to ignoring the hand with which the magician is gesticulating wildly and instead concentrating on the other hand.

She does not mean to suggest that you intend a sleight of hand, but one is nevertheless in progress. Revealing the trick requires only that we remove all 21st-, and perhaps also 20th-, century technology from your question.

Your wife is excited by, and wishes to share, news of a friend or acquaintance of hers you do not know. Is this interesting? Possibly not. Are you required to show interest? Of course. Is it also reasonable to expect some limitations on how much time and energy you will have to devote to feigning an interest you do not feel? Yes.

All of these things were true before the internet and will be true when our children’s grandchildren dismiss social media as hopelessly old-fashioned. Discovering that you object to social media on principle does not remove your duty to show interest in your wife’s interests. But a discussion about how many baby videos constitute sufficient interest is in order.

DEAR MISS MANNERS: What is the proper way to tell a friend that his or her son needs a haircut?

GENTLE READER: Etiquette can accomplish many wonders, but not one that goes against its nature: Commenting on someone else’s grooming is inherently rude, and commanding others to do something about it, more so.

Although it would not, strictly speaking, be rude to tell your friend how nice her son’s hair looks when it is short, Miss Manners warns you not to expect an appreciative reception if you try.

(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, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: I have a niece who shaved her head for a childhood cancer charity, and she has received a lot of comments such as, “That was so brave of you to shave your head considering you’re a girl.”

I am beyond disgusted to hear this, but I can’t think of what she could possibly say that would both alert the commentator to their veiled insult and still express a level of politeness.

GENTLE READER: It was in the hope of educating the general public -- and thereby sparing future cancer patients such unkindnesses -- that charities started encouraging non-patients to shave their heads. This being the intent, Miss Manners suspects that your niece will want to respond on point, rather than getting distracted by the implied gender issue.

That can be accomplished by saying politely, if solemnly: “Thank you, but what I did is really nothing. Just imagine what those children have to endure.” The commentators may conclude that your niece is being sanctimonious, but they will also be discouraged from repeating their rudeness to the next compassionate person.

DEAR MISS MANNERS: The cafeteria in my office building includes a large salad bar, which I often frequent. The setup is fairly standard: greens, then proteins, then a long stretch of other toppings before finally getting to the dressings.

Often enough, I find myself with my salad fully assembled to my liking, but I am stuck behind someone who is moving down the line adding more and more toppings.

If there is no one else in front of this person, is it acceptable for me to cut ahead to the dressings? On the one hand, I feel that cutting for any reason would be inherently rude. But on the other hand, I’ve had someone ahead of me act apologetic for “taking so long,” or rush through their selection because they feel they’re holding me up. Of course I wouldn’t dream of skipping ahead if there is an actual line of people. But it seems silly and feels awkward to just be standing there waiting.

GENTLE READER: It is always rude to cut in line, but the situation you describe is not always properly considered one line. (Miss Manners is fond of subtlety, not caring that it is sometimes derisively referred to as a technicality.) You may jump over a substantial gap. Ideally, find someone on the other side of the gap and line up behind them as a demonstration of your law-abiding nature.

DEAR MISS MANNERS: I have a friend who promised me several times to pay me back for an event ticket if I paid the money up-front. He finally came through a couple days before the event, but I didn’t have the ticket on hand, so he said he would pick it up in the next couple of days or meet us at the event.

He didn’t pick it up or show up at the event. My friends and I tried calling him several times, but we didn’t get a response, and he hasn’t called me since.

Should I make an effort to pay him back, or wait until I hear from him to see what he has to say? I don’t want to get rid of a friendship over the ticket, but at the same time, I am very upset by his behavior because I could have spent the money on other things.

GENTLE READER: As you already have the money in hand, it is not a question of how to spend it, but whether or not to return it. Your friend would no doubt say that he paid for the ticket, as agreed, after which it was up to him whether or not to attend.

Miss Manners sees the logic in this without entirely accepting it. His paying for the ticket did lessen the host-guest nature of the invitation, making his nonattendance less repugnant than, say, missing your wedding. Assuming a formal apology is therefore not necessary, your wisest course of action is to treat the matter as closed, and proceed with the friendship.

(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, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)

DEAR MISS MANNERS: Lately I’ve found that chain restaurants, and even local ones, have a tip line on the credit card form -- when the restaurants provide no service.

I place my order at a register, pick up my food when they call my name or number, and then bus my own table. They clearly expect you to do this, as they provide receptacles and signs with instructions.

They have a tip jar for use if you don’t use a credit card. I understand this is a practice at coffee shops to show appreciation for the artistic ability of the barista, but for a plain cup of coffee? I’ve also found this practice when I pick up a meal to go.

I understand this is to offset the fact that they do not pay a living wage to the employees, but am I required to tip when no service is rendered? I usually end up putting $1 in the tip jar or on the tip line, which makes me feel churlish and taken advantage of at the same time.

GENTLE READER: There are a number of factors to weigh when deciding whether or how much to tip, but Miss Manners does not consider that the little tip-bait traps have become so prevalent should be among them.

The most important element is whether the job is structured so that tips are counted as part of the workers’ wage. (For that reason, owners of businesses are not tipped, although many have also come around to expect it.) Miss Manners believes that service charges should be built into the customers’ bills, not left to their discretion. If that is not being done, however, she cannot countenance customers withholding such basic compensation.

Less important, to Miss Manners and practically no one else, is the quality of the service. Blatantly bad service should be reported, she believes. But before penalizing someone merely for having a bad day at work, one should reflect about whether one’s own income is affected by an occasional lapse.

And while it is generous to reward good service beyond the customary minimum, it is insulting to maintain that workers are so unprofessional as to require extra bribery in order to perform their jobs well.

So you should tip when you think it is right. But do not have qualms about not doing so only because the business is trying to make you feel guilty if you do not.

DEAR MISS MANNERS: While discussing with some colleagues a family member’s plans for a black-tie wedding and reception, someone noted that gifts are not to be given if the wedding is black tie. I have never heard of such a thing, and my husband and I have already purchased a lovely gift. Clarification of this matter would be appreciated.

GENTLE READER: Amazement, rather than clarification, is the only thing Miss Manners can provide. Where do these bizarre ideas arise? What possible connection could there be between the clothing worn and the presents?

Folks, please stop making up absurd “rules” that you try to pass off as required by etiquette. Miss Manners has enough trouble making people obey the real ones.

(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, Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO 64106.)