Dance with the Dragon Duke by S. L. Prater

For a desperate duchess, an Unseelie duke could be the perfect fake fiancé.

A fae woman named Tomorrow is set to inherit a wealthy duchy. The one stipulation: she must marry a man of gentle breeding. But to make it to the altar, she’ll have to survive her family first. The next in line will stop at nothing to keep her from collecting.
When she’s introduced to the Unseelie Duke of the Dead, she’s certain he’s the partner she’s looking for. He’s dragon-strong and just as big and frightening as he is handsome. Most importantly, he appears to be as down on his luck as she is.
The Duke of the Dead …
Darko lost everything to war and a tyrannical father. When Tomorrow approaches him with a promised fortune and an offer to act as her pretend lover, he’s intrigued.
As they work together to thwart her enemies, a mate bond begins to bud between them, but Tomorrow has secrets she’s not yet ready to share. She warns Darko against forming an attachment, but what happens when the duke is done playing pretend?