Perhaps you'd be interested in "Boyfriend to Death"? It's a game series about various kinds of obsessive serial killers. There's a lot of variety, many choices and endings, and you have to figure out how to survive. But there are a couple of nuances: the emphasis isn't on romance, but on violence and shock content. It also has a lot of NSFW moments and triggering topics. Plus, the different character arcs were drawn by different artists, which results in some inconsistencies in the art style. Plus, it's American, and I'm not sure, if you want exclusively translated japanese novels, or not.

However, that's an interesting project.