The Viscount, the Blacksmith, and the Lady by Ari Thatcher

Simon Cooke, Viscount Kinnerton, has been friends since childhood with Xenia Arbuckle and Owen Bishop. The two men have loved Xenia since they were teenagers, but they made a pact that neither of them could have her, for fear their friendship wouldn’t withstand the heartbreak of being the one left out.
Xenia has turned away any suitors she’s had, and at twenty-two, her parents are hinting she needs to marry. She secretly loves Simon and Owen and was certain one would eventually propose to her. Deciding it’s time for her to take control, she steps up her flirting and challenges the men to prove which man is the better lover. What starts as a kissing contest becomes oh, so much more.
Owen and Simon have shared women in the past, but never one they loved. Jealousy arises quickly, and neither man is willing to walk away from a lifetime with Xenia. Can they find a solution they can live with for the rest of their lives?