The Fire Lord's Lover by Kathryne Kennedy

The place is England in 1724.  Mankind is subjugated to the rule of seven dissident elven lords, who broke free from their land and came through the gateway that separates the lands.  Having magic and strength on their side, they quickly managed to take over the country and now rule it, each lord in his own territory.

The strongest elven lord, Mor'ded, rules London with an iron hand.  His power is that of fire.  His main general, Dominic Raikes, is also his bastard son.  Dominic is half-human but has learned to suppress any human feeling as Mor'ded just uses it to torture him, killing his pets and friends to teach him not to get attached to anything. 

Cassandra is a sheltered young woman who has been raised to become the bride of Dominic.  She also has a secret; she has been trained as an assassin by the Resistance.  The Resistance are those human who want to throw off elven rule and restore the human king.  She is to marry Dominic, and use her relationship with him to get close enough to Mor'ded to kill him.

When they meet, nothing goes as planned.  Cassandra is shocked and humiliated by Dominic's unfeeling treatment of her and his flaunting of his mistresses.  Dominic is determined not to feel anything for Cassandra, knowing that to do so will doom her.  Yet, they both hate and fear Mor'ded and as time goes on, create an alliance to try to defeat him.  Will they be successful before he discovers their feelings and destroys them both?  Can Cassandra and Dominic manage not to fall in love?

The Fire Lord's Lover is Book One of The Elven Lords.  Kennedy has created an interesting world, with enough historical grounding that the reader feels familiar with the background.  The love story has the reader curious and makes them want to read to see how it will work out.  This book is recommended for fantasy readers.