Putting language to something for which you have no language is no easy feat.
I think what Machado is trying to do here is use the Biblical story of Genesis to point out what she is trying to do with this book. She's trying to put her experience of domestic abuse in a language no one has put it in before. Especially when domestic abuse in gay relationships is not talked about anywhere. It must be difficult for her to put her story into a language that it is never put into as a story written in different genres. The "fuzzy thing" is something unknown to Adam and it seems like it can be compared to the relationship Machado is writing about in her book since domestic abuse is something with not much attention since queer relationships are still a thing frowned upon by many people today.