A disease (or rather, trend) that most modern day romance (and romance-comedy) anime have these days is that they avoid the “darker” issues of infatuation. To them, infatuation is like that first crush in high school: bright, mellow, sometimes bittersweet. The male and female protagonist will end up together, their love made clear by their first kiss delivered amidst a resplendent background, often times with their comrades in the background, cheering “You look great together!”
But rarely do they attempt to trespass into the much darker, Freudian-esque territory, of raw dejected desire and unrequited love. The sheer taxing burden on one’s soul when one gets rejected or sees the love of their life being stolen away by a cunning vixen and being helpless to prevent it is almost never explored; and if it is, it is written off comically. This is where Kuzu no Honkai attempts to go; into the pit of despair, the graveyard where love goes to die and gets replaced by banal desire.