Written as a sequence of theorems (each numbered, stated, and then "proved"), it tells the story of someone in a long distance relationship with an astronaut.

Since the story is so short (and so good), I would urge you to obtain a copy and read it yourself before I get to any "spoilers" below.

It was published in the "Futures" column of Nature in February 2023 (doi: https://doi.org/10.1038/d41586-022-04195-1). I am very grateful to Allan Goldberg for noticing this short story and bringing it to my attention.

The formula s=d/t comes up in each of the theorems all the way through "Theorem 1.5: The end-of-the-world theorem". Here it is revealed that the astronaut was attempting to save the planet Earth from an imminent disaster, and that the attempt was unsuccessful. Consequently, the value of t approaches zero, representing the infinitesimally small amount of time they have left to live. Under these circumstances, the formula takes on a whole new meaning, as does their relationship.

To me, this was a very clever way to use mathematics in a work of fiction. There are a few other works that I find similar to this one in some ways, especially Division by Zero and Problems for Self-Study, but this ending still seems quite unique to me.