I read Either/Or about a year ago, and had a very similar reaction to you, I think — I liked it better than The Idiot (which is saying something, because The Idiot was my favorite book of the year I read it in), but also definitely had the same concern about Selin that you're talking about here, with an intensity that was kind of alarming. I wrote in my paper journal, the day I finished Either/Or, "I am burning to read the unwritten sequel to Either/Or, because I want it to all be better for Selin.... Selin seemed more real than almost every other fictional character I've come across." I had the sense that Either/Or was less autobiographical than The Idiot, at least, which would be some relief if true, though I'm not sure if it actually is.