What The Heart Needs (Stars Landing #1)
Jessica Gadziala

She spends long hours catering to every need of her rude, condescending, and distant new boss finding that, despite her better judgment, she feels a growing attraction to him. Just as she is contemplating all the possible reasons an affair with him would be a terrible idea, mysterious letters start showing up threatening her to stay away from him.
As the threats start permeating every aspect of her life, Hannah is thrown into a dangerous situation and is faced with a difficult decision: run back to her hometown and into the arms of her high school sweetheart Sam Flynn, or stay with the smoldering Elliott Michaels despite the mysterious tormentor getting ever closer.
* The Stars Landing novels are all independent and stand alone books that can be read as a series. For those interested, this is #1 *