unless Sophie and AW were a lot closer than I imagine they were

Well, AW was passionately in love with Sophie and fainted at her wedding, and Sophie had agreed to marry him, only Fritz said no, and rather than have extramarital sex, she decided to tell him no and marry someone else. See here for selenak's writeup. So I could see AW's public humiliation and death having marked emotional impact, even a few years after she married her second choice. Of course, I haven't actually read up to that point in her diary, so I don't know what her feelings were at that point.