@GoldenSpin My guess is that this chapter is meant to be set up for a bit of drama. I doubt its going to be bittersweet. If the letter is from her parents, I expect him to all but yell his intention to marry her to them when they arrive.
When she came to his school for the first time everyone was talking about her. I was wondering if she was a previous noble or something, but this makes more sense. At least there’s an explanation why she said she’ll work without a salary.