I recently discovered Scum’s Wish from an article describing the relationship between Mugi and Hanabi as abusive. While the anime begins with Mugi and Hanabi both in love with other people and only using each other to satisfy their physical desires, is there really anything inherently wrong with this? People have casual relationships all the time. Not all relationships are built around love.
Not only that, but, I think that love is a feeling that can grow over time. Hanabi and Mugi may not be in love just yet; but that doesn’t mean they won’t fall in love by the end of the anime or manga. There has been much foreshadowing already hinting at this possibility.