I mean, if we have to be critic, this is obviously following Nana to Kaoru steps.
The difference is that in Nana to Kaoru, the romance was built later into the story, as a consequence of their interaction. But for the most, the focus was on the bdsm aspect and the erotic vibe it created.
In this one, on the other hand, romance and eros/bdsm started together and are still going together. They are kinky because they love each other, and love each other beacuse they are kinky.
Now, for other works, Idk what you're reading, but I think the reason they go straight into erotica/soft-porn is because bdsm is still seen as just a kink, a twisted way to have sex. Especially for jousei and femdom in particular, it's just seen as something perverted, with almost nothing romantic.