This isn't just a story about S&M or fetish anymore. At least not to me. It's a story about how two lonely people (her isolated and him inferior) can feed off each other once they establish a link. Whatever that link is or how minor it is. Minezaki shares her fetish because Sawada is kind and won't use the knowledge to his advantage. Pretty tenuous, right? But then Sawada accepts the link and takes on the role she wants him to. No she's getting both bolder and more attached. So is he.
If this had a psychological tag I would expect it to get super-dark next. More dependency feeding more connection feeding more isolation from others feeding more dependency on each other. But that tag isn't there. I think the author is going to attempt to flow into a more conventional romance manga. And I think they have a shot at actually pulling it off.
Or they won't. We'll see. 🤔