It may seem confusing since the story's going back and forth between the present (where Sa-il is helping his mom) and the past, but as I undertood:
His father made a portal between the lake and their house in the forest, so he went back to see his wife but would come back for Sa-il when the patch is done, or maybe to visit from time to time too.
After that the story skips to the present where we meet Sa-il's little brother, and when he appears says that their dad escaped from doing ehh.. whatever Sa-il's mom is making him do xD
So from that we can assume that his dad went back to the lake after the patch was done and brought him home, just that the story didn't show it. And that right now he's skipping house chores.
I hope I wasn't too confusing (￣∇￣")
ohhh i get it nowwww// thankyouuuu/// i thought smth bad happened to the father. and i dont want that to happen. goodness. **anxiety was attacking mE lmaoooo**
y leave it like that tho? author-nim got lazy perhaps? hshahahahaha **jusT kidding author-nim
Haha xD Maybe the author didn't think it was necessary to show it explicitly, but I'm glad I could help (๑•ㅂ•)و✧
wait. am i missing smth? where did sa-il's father go?. yes i clearly saw hes going to go back to their home but after he left (father),they didnt mention him again. he didnt even went back to sherry's place/lake.
now,its already the time where sail is already an adult. omg pls enlighten me. im lost