Can anyone tell me if there is a genre for historical romance/murder mystery/psychological thriller?

Judging by the first chapter, the title of your story and the thematic elements in your question, I say you are writing a Gothic mystery popular in the 1800s and set in in the 1800s-Gothic Literature has always had romance in it, even if it is a Gothic mystery. Gothic mystery writers include Wilkie Collins, Edgar Allan Poe, and Robert Louis Stevenson.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.