Sounds like a good old fashioned Gothic ghost story to me! I'm also in agreement that, based on your brief synospis, it would currently probably best market to publishers of paranormal romance, BUT that is also going to depend on the "romance" meter. Barbara Michaels (who writes under multiple pen names) successful published a number of ghost stories with a very light romantic element: Ammie, Come Home, Be Buried in the Rain, Here I Stay. Her works usually involve a subplot from the past going back a hundred years or so, a "free the restless spirit" kind of thing. Julian's House by Judith Hawkes is a terrific ghost story published in the late 80s, not too strong on romance (if I remember correctly), but with a decidedly contemporary element of sexual tension. Then you have Anne Rice, most of whose works can be considered "gothic" and "romance" and "paranormal" though they don't follow either of those genres formulas. John Saul has had a long career of writing ghost stories. I read one of his books every ten years or so. I don't care for them based on style and substance, but people buy them and eat them up.
Ultimately, I guess it's going to be up to you to decide what you want to call it when you submit your query, and be prepared to change the "genre" for different publishing houses. Just as an example, Bantam may like it but may not be after "paranormal romance" and will react better to a manuscript called a "comtemporary ghost story" whereas Kensington's "romance" editor would readily read something "paranormal" but might see the "ghost story" label and pass it off to their "horror" editor who reads a few pages and realizes it's not "horror" and back it comes. Also, you might want to be prepared if an editor comes back and says the story is great, but can you slant it more toward ______ (romance/horror/psychological thriller) which would require some major rewrites but hey - a sale is a sale!
That said (it's early, I'm rambling, but my point is near) I'm having the same issues with my own work in progress. I have been writing for a year and a half, and was initially writing for my own entertainment, but now after about 30,000 words I am considering such things as genre markets to try to tailor it toward marketability. My original concept was very much in the gothic tradition (young couple inherits old house) but it morphed into what I can only call a "Southern Gothic Family Psychodrama." (I got rid of the couple). Unfortunately, that path has led me far afield from the supernatural. I may no longer be writing the book I thought I was writing. Only time will tell. At the moment I wouldn't even be able to market it as a "supernatural thriller".
Anyway, good luck with your MS. If you post it for reading let me/us know. I'd take a crack at it.
) -- genre can be difficult to pin down. 
