Yeah this is what ruined Tempest for me too. Dropped immediately.
I was soo disappointed because I love Jun Ji Hyun and wanted to get into it but just couldn't, she's how I got into Kdramas like 3 years ago with My love from the star and The Legend of the Blue Sea.
I don't think she did .. did you watch the scene after the credits ?Her mom looked too calmed after one year..so…
I had to do a double take but there are more clues like the white flower blooming, the fish healed and had a buddy, the his and her tooth brushes in the bathroom.