You might find writing guides relevant to your interests. For example, “How to Write Science Fiction and Fantasy” by Orson Scott Card contains some details about how the author came to write Hart’s Hope and other novels. “Scene & Structure” by Jack Bickham might also be interesting – I don’t remember discussion of specific books in it, but it might scratch a similar itch for how-it’s-made style content.
Some books also contain introductions/forewords/afterwords with details about how the book was written. A bunch of OSC’s novels (like some editions of Ender’s Game) come to mind specifically – I read those back when I was curious about maybe trying to become a writer, so that’s the most prominent example in my mind, but I’m sure there are others. I’ve also seen translations of a number of works where the translators include really long introductions explaining some of their choices – and sometimes criticize earlier translations.
I’m not sure if I’ve ever fallen in love with a completely imaginary dream person, but I did dream about my ex once years and years after we broke up. I don’t remember what I dreamed about exactly, but I do remember waking from it. The happiness fading as the realization set in that it was all a dream – I was by myself in bed and none of it had been real. I’m usually pretty good at dealing with solitude, but that moment… that was the most intense loneliness I think I’ve ever felt.