It's not easy creating a detailed yet concise short story, so I tip my hat to you and how effortless you made this look. I enjoyed the descriptive details such as Kearsarge's worn hull and Dan's thoughts on the bridge layout. And the crew was fleshed out just enough to make us care about them. The Kearsarge and her compliment were made just as "real" as any other Starfleet ship we've seen in fandom.
As much as I like temporal loops, it was the elements above that gave the ending real weight. In fact, I think you made the crew too interesting. Now I sort of want to see more of them!
Oh well. Fantastic work. You've taken a well worn ST plot device and actually made it scary.