This story was like the happy version of this other story: http://www.mangago.me/read-manga/haru_ni_kaeru/tr/172001/page/
what is this world coming to
It's more like he's in love to a dryad... the spirit of a tree. Trees and plants are living things with a soul, so it's not weird to fall in love with it.
Notice when you see something beautiful, like the sunset perhaps, or a view so magnificent and beautiful? The feeling you get at that moment is like falling in love right? It's because you see the Life in those things, and if there's life, there's a soul... Souls are just like a concentrated essence of life, so anything with life has a soul no matter how small... Some of those souls receives consciousness, like spirits, and most spirits has physical forms, like humans and animals and plants.
And this knowledge has been around long before us, since life started before us. It is simply that, we tend to disbelieve anything that wouldn't fit into our individual reality.
The irony is that many things Clark says about Alexis is really about himself (ex: you just see the doctor as a pet; clearly Clark felt that way too since he fed the dude's finger to his fish at the end lolol). And the title, is really we the readers are 'interviewing' (IE reading about) a murderer (Clark) who truly killed in stone cold blood, in a way Alex did not.