DEAR MISS MANNERS: My wife and I have the good fortune to be co-owners of a house near the beach. When we can’t use it, we often offer it to friends for the weekend or the week. This is a community where many of the houses are rented during the summer at rather high rates.

I am surprised that while our friends have thanked us (usually just an email), there has been no offer of any reciprocity beyond that, and often the thank-you seems rather perfunctory.

In particular, one close friend has stayed there five times. After her last stay, I wrote her an email suggesting that she might want to buy a small item that we could use at the house. I never received a response to that email, and I thought that perhaps the email had gone astray (it happens).

But the last time I saw her, she mentioned that it was still “at the top of her mind.” Now a half-year later, we had already made that purchase, and I told her so.

I know that she, her husband, children, mother, father and aunt enjoy their time at the beach, and when we can’t use the house it seems silly to have it go unoccupied. But at the same time, I feel like I have been very generous without any sign of reciprocity.

Suggestions? Or should one just realize that generosity is its own reward, and if that is not enough, stop offering?

GENTLE READER: That generosity should be its own total reward, to the extent that it is defiled by the expectation even of any acknowledgment, is an argument with which Miss Manners is only too familiar.

But she generally hears it from youngsters who are indignant that their selfish grandmothers expect them to say they received presents she sent. Instead of troubling them, why not just look to see if the checks are being cashed?

This is not an argument that charms Miss Manners, even when it is bolstered by recitals of how many other demands there are on teenagers’ valuable time. She does not have far to go to find greater examples of selfishness than that of hoping to hear that one’s attempts to please have been successful.

In your case, you can presume that these people like the beach house, because they keep coming back. What is lacking is any sign that they actually like you for providing it. Surely if they did, they would invite you to visit them, or otherwise exhibit gratitude (in more than a five-second email) for this enormous annual favor.

Personally, Miss Manners would be thinking warmly about strangers who pay those rather high rents. Call her selfish, but she thinks of it as saving those friends from the selfishness into which they have sunk.

DEAR MISS MANNERS: What is the best response to people I know casually and to strangers that tell me to smile?

GENTLE READER: “Say something witty that I’ve never heard before.”

Miss Manners is the pseudonym of Judith Martin. Contact her at dearmissmanners@gmail.com.