Story Idea: Twilight Exit

Normally my story ideas start and grow to book length, but this story seems to be a natural short story. This came to me as I watched twilight come on next to our new pool.

A father and son arrive at a vacation home in the woods. They settle by the pool as the sun begins to set. The son is wearing headphones and the father monologues about the changes in the natural world as the sun sets. The father talks about a "switch" where the day changes to twilight. He describes it as a hiccup, where everything changes from one state to another. That in that time, there's seems to be an opening where things are open, undecided, before setting down again. From the father's monologue the reader understands that he has regrets about his son, his family, and his life. The father describes how the bats will come out later, after the sun has set for awhile. The monologue ends and the son finally notices that the father is no longer around.

Outline
Father & son arrive, settle around the pool.
Father starts the monologue. He's addressing the son, but the son has headphones in and never responds.
The home has been in the family a long time. The father says he has always felt a special connection to the sunset. He has spent many days through the years, watching the sun set by this pool.
notices a eagle returning to it's nest
smaller birds venture out more as the king has left the sky
closer to the pool the dragon fly come out, darting in various directions.
reminds him of the "invisible feeding frenzy" where dragon flies and sparrows would take turns feeding on a swarm of tiny white flies. The predators would take turns attacking the swarm. Not sure why the sparrows avoided eating the dragon flies, but they did. He tried to take pictures, but his phone could only capture blurry pictures of the birds and dragons. The white flies of the swarm where hard to see with the naked eye and invisible to his phone's camera.
How does the dynatrap work?... the father's theory that the trap works by attracting moths, that attract bats, that eat the mosquitoes when the are in the area. Mentions the bats will show up a fair amount of time after the sun has set.
The father mentions the setting sun touching just the tops of the trees. Soon there will be what he feels like a pause between the day and evening. Not between day and night, as the twilight has a unique process to itself, but between the day and the twilight. The pause seems endless even though if you try to measure it, it disappears. Nothing happens, and yet it seems like an invitation, a path through the woods you notice for the first time, but it was always there.
The son's phone loses power and he notices the father is no longer near by. He calls out with no response, but the car is still in the driveway. The son goes into the home to find power for his phone.

This story is a bit of downer.