it's easy to forget yukiko is a total freak after just reading a room for two for a while
I feel like it adds a lot to A Room For Two. You see this superidealized relationship with almost no conflict and perfect devotion. Beneath that is someone who understands monstrous desires. Helps you understand what lies beneath the fantasy of Sakurako's slavish and absolute devotion to a cool beauty utterly dependent on her.
I think I read someone read A Room For Two as a wish fulfillment story about having a Sakurako, a perfect devoted waifu who will take care of everything. I can see that. Personally, though, I see this more as a fantasy for Sakurako, to have an object of absolute and unending infatuation that, despite protests, will ultimately accept you regardless of the intensity and strangeness of your obsession.