TLDR: if you can't feel pity or empathy for mentally disabled people always being rude, and you would treat them like you would a normal person without some unhappy background, then don't read it. Also don't read it if you're only here for the romance. Overrated.
It basically goes like this: the girl does something insane (because she is) -> guy says it wasn't ok -> she cries -> guy remembers her early-on suicide attempt and consoles her -> they both grow a bit -> step 1. It's some kind of a pathetic roguelite pity-fest, as stupid as it sounds.
I'm sorry for the harsh words, but I simply can't feel any remorse or sympathy for the heroine. She treats anyone like garbage and this behavior even rubs off on the MC, as he tries harder to understand her. Sure, she has a reason to be like that. Yes, she had a horrific childhood with no-one to support her. However, the only thing I can say is...
...so what? Why should I care? I'm not a nurse at a mental institution to need to feel compassion for her. You hate people for being normal? Well, tough luck, I'll hate you too then! Maybe I just lack any empathy, but I don't consider a disability a reason to be an asshole. If you want to be treated like a normal person, treat others well. It's not her fault for being born like this or having bad parents, but no one is obligated to excuse her behavior. The girl's personality characteristics fit a main villain more than a main heroine.
I obviously can't understand her; neither do I want to.
From what I've hear from other people, as the story goes on, she and the guy make progress in fitting into the society. I'll be frank, I came here only for the romance, and slice-of-life doesn't really interest me, so I can't make any comment on how things go.
I don't know how the romance unfolds in the later volumes, but unless there's some kind of a fallout due to their codependency becoming dysfunctional, or another love interest making an entrance, or some other love trouble to shake their little world, there isn't much weight in the romantic aspect of the story. And even if there is, it wasn't worth suffering through other crap for me.