Paranormal Romance & Urban Fantasy discussion

I've been trying to find a book that I read a few years ago. I figured that this might be a good place to start.

From what I remember, part of the plot included a girl (possibly a princess or lady of some sort) who was kept in a tower or room. An incubus started to visit her at night so she was given a necklace to ward off the incubus. The incubus managed to convince her to take it off. There was also another subplot and it was set in a fantasy realm (not urban fantasy).

Any help or recommendations about what this book could be would be greatly appreciated. I know it's not a lot of information to go off of. Thanks in advance!

Laura--there is also a group here in GR that is dedicated to nothing but helping people find a forgotten book title. https://www.goodreads.com/group/show/... is the link for getting to the group.