Dark Romance. Serial Killer Main Characters. "Dont make me kill you in your sleep" "Dont flirt with me like that"

[yves𐙚]

I am looking for a book I saw in an Instagram reels a few months back. I dont remember the title or the author name. The video was just a snippet of a conversation from the book that went like

"Dont make me kill you in your sleep"

"Dont flirt with me like that"

The conversation might be different in words but i remember this from the video. I think both the main characters were serial killers and i am so sure its a dark romance. I saw this video in the last months of 2023 and I am not sure about the publication date either. But this book keeps me up at night so please help me find it. Thank you💗

[Robert]

Google advanced book search brings up Please don't make me kill him, it seems to be a match

[Kat]

If it's not that, any chance it's Butcher & Blackbird?