I have had penpals since my teenage years, am now in my 70s and believe it or not, I am still in touch with a handful of the very first ones. Along the years, of course, some have come and gone, many have stopped writing, sometimes after a good-bye note, sometimes they just vanished.
Whenever I felt like breaking a connection, I did write a short explanation, sometimes I am afraid not very convincing, because I could not manage to say things like “we have nothing in common” or “I feel no common ground with you”, so I mentioned a change of circumstances in my life or some other vague “story”. However in the case of those exchanges of letters that were leading nowhere so to speak, the other party usually vanished at a time or another.
Some vanished for no (for me) understandable reason, but one has to consider that when a penpal dies or becomes severely incapacitated, there is not always a relative or good friend who can or takes the trouble to write about it to the penpals. In many cases, a relative or friend DID write, and it was a relief to know what had happened. But when nobody could or was willing to write, one is left wondering… Of course one can guess if the person was previously in a bad health with severe issues. Sometimes the post-office will return the letter with a sticker saying “Deceased” (what a shock it was the few times it happened) or “the person no longer lives at this address” (this happened to me twice with a pen-friend who was very unlikely to have moved as she had a farm. I did write again and it proved that a new postal employee in her village has made a blunder…The other one lived in a city and it also was a mistake by a newbie postal worker as I had in both cases written the address with no mistake).
In the case of postcard-only-penpals, I usually stopped (with a note) when I had no more cards that were adequate for that person, or when the person kept sending the types of cards I had asked not to send…
Hard to read handwriting can be an issue, also a person who uses a translation system. I stopped some exchanges of letters because I could not make head or tail of what the other person wrote due to bad translation. In one case I stopped a correspondence with a penpal of many years when she became addicted to a religious sect and kept sending me unending quotations of the Bible and such inappropriate material, even though I had repeatedly asked her to stop. I enjoy discussing about religion, but not being machine-gunned with childish religious propaganda…
What else to add, I have met quite a few of my penpals along the years. Sometimes it led to a long-lived friendship, sometimes , well, the meeting was a bit disappointing and afterwards the correspondence petered out. But as some said rightly in other messages, pen friendships are exactly like friendships in real life, some “take”, others do not, some last so long as both parties are on the same wave-length, then slowly or suddenly die.
Sometimes the situation in the country of one of the penpals causes such upheavals that it becomes impossible to exchange letters, either because of armed conflicts or some other political reason, or just because the postal deliveries are too disrupted. And in a case like the current situation in Russia/Ukraine, or about other international news topics, some persons will take offense if the other one expresses ideas that he/she does not agree with…
Right now, in China where I live, the normal flow of international mail has been badly disrupted since the beginning of the pandemic, at first. due to the epidemic situation in many countries, that led them to put their mail system into dormancy, and now the problem has been compounded by the many lock downs in China (and so far as postcards are concerned, the difficulty of finding many kinds of cards that were easy to buy earlier). This has led me to stop most of my postcard swapping and has badly disrupted my snail mail correspondences. Some friends have accepted to switch to e-mail correspondence, some have not, and some cannot as they have no access to e-mail. Thus I lost most of my non-e-mail correspondences with Canada, as since the pandemic started, the mail to/from that country has taken around six months each way.....And it has been about the same with a few other countries even in Europe.....
As in addition, there is also a strong possibility of my soon moving to another country, most mail taking months to reach me would get lost…
So the world of pen friendship is as varied and complicated as the real world… I have always enjoyed being a part of it and will continue as long as I can!