One Side Soulmates

The siblings Emmeline and Timothy comes from a family, with their parents almost always absent. Because of that they get a governess, Cordelia, to make sure they get the education needed.
Only after being with the family a few weeks, the children open up to her and they have lots of fun together. But even though there's a war going on and Cordelia hasn't been with the kids much yet, the parents leaves for a trip to another kingdom, with the children left behind.
All while Emmeline the oldest gets an interesting journal, written by an mysterious woman, that their governess somehow knew. But with no good ending, she tries to find the mystery woman, needing to have the journal finished correctly like if it was a book. But what would the ending be?