Eklund has been writing high-quality SF as long as I have been reading it, and I’m pleased to say that this story is of as high a standard as his best (not always the case with authors decades into their career).
The protagonist is probably as unpleasant a character as you will find – bad enough that he’s the one causing the imminent end of the world (we never find out how), but he’s a Douchebag with a capital C (my description and capitalisation).
He’s extremely uncomplimentary about his wife, and entirely self-absorbed and obsessed, and thrown out of the house by his wife, he throws himself at the mercy of his sisters. One is a writer (who writes novelisations of old TV series, a neat touch once you know wiki was a novelizer of Star Trek TOS Back in the Day).
The story follows him through the last hours, as another sister (memorably outfitted in an outfit that Paul Di Filippo could have dreamt up) helps point him in the right direction (looking up as the stars go out).