Not only is this a sex-ay cover, but the story is pretty darn good, too!
Shadow Touched (Shadow Touch #1-4) by Erin Kellison
A darkness looms over humankind, lurks in mirrors, blurs boundaries—a twilight world ruled by powerful mage Houses...
It is bleeding into our world, bringing with it banshees, wraiths, fae from the twisting forests of Twilight. But Eleanor Russo’s problem is a very different kind of phenomenon. Her dark mirror image is a wild thing, willfully seducing the very man Ellie hoped could help her.
Dr. Cam Kalamos has devoted his career to exploring the boundaries between this world and Twilight. But nothing could prepare him for the mischief and mayhem of a soul split in two.
As Ellie and Cam explore their deepest desires and barely escape with their lives, there is only one certainty: Trusting in shadows is a dangerous game.