Responses
https://www.mangago.zone/read-manga/gachi_koi_nenchakujuu_net_haishinsha_no_kanojo_ni_naritakute/
It's more of a dark comedy than a psychological manga, but the relationships are a pretty fun sort of messed up.
I Reincarnated as the Little Sister of a Death Game's Murder Mastermind and Failed
Bastard
Garden of the dead flowers
Annarasumanara
psychological or dark romance rec pls ? recently, I found a story called "Locked To Death" and it's surprisingly good, the female lead (a mermaid !) is twisted and she's the "touch him and you're all dead" kind of girlfriend (except they're not official yet)