American Prince by Sierra Simone (American Queen book 2)

The world thinks Embry Moore a prince, but I never coveted the throne. Only those upon it.

When I was young, I learned the bittersweet truth about loving a hero: it can never last.

Twice Maxen Colchester asked me to be his, and twice I turned him down. I thought I was protecting him, but I made him suffer. And now it should be my turn.

I've made sacrifice after silent sacrifice for the best man I've ever known, first in war and then in love. I've only just now found my way back into Ash's arms--and into the heart of his wife. I haven't forgotten the pain that led us here. Nor do I know how to prevent more. 
So I'll let him punish me for the past, and hope to store it against the future. I'll be his man. I'll fight for our woman. I will do my duty as Vice-President. But I was always born to suffer. And when Greer is taken from our bed, it sets in motion a series of painful revelations that threaten to turn our years of tortured love against us.