It was stated before that both her brothers were drafted during the war. Her older brother came back severely injured and her younger brother was killed in the war.
About the tutor, I think he was apologising because he couldn't help her pursue her dreams and further education as women's education weren't as developed before. Even noble ladies used to receive education on how to become proper ladies and nothing much complex or other matters even if they wanted to, the thing that happened to Anna. So Charlotte had to leave to become a maid, I think that's why her teacher was being like that because there wasn't much he could do for her even if he wanted to.
Is this really the end? Waaaah... I mean, the story about Charlotte's past hasn't been revealed yet or has it? Just like the story between her and her tutor (the one who taught her), it seems like something happened and also the story with her younger brother, it's not cleared yet. T_T