The Splintered Princess. The Ever Spirits, #1

A magic dagger. A beautiful man. And me. We were a match made to be destroyed. My life was sunrises and wheat fields and artless days, a sequestered, featureless existence. Then a visit to a bustling market brought me to a mysterious dagger, which lured me in with whispers that I was meant to be an empress. Daring to dream of power and love, I picked the dagger up. And I reached for him. Avid and ardent, we were vicious in strength and feral at heart.
But he protected those he loved while I-heedless, slapdash, rash with my emotions-played carelessly with the lives and hearts of those around me. Family? Friend?No one was safe. My country's overlord kidnapped my parents and siblings to force me into a charade: train to become a decoy princess to protect his queen. I must hide my identity-while also hiding the spirit of the man I loved, the strip of soul that my beloved ripped from his being while he was agonizingly tortured by our common enemy.
This is all that remains of him: a spirit-boy grasping our doomed and tormented dreams. He urges me not to lose hope, to trust the promises of the dagger, but as secrets come to light in my overlord's castle, and my love's true self warps into an atrocity who mocks and taunts me from afar, I realize that becoming an empress will cost lives that it will break me to lose. NOTE: This book is not a fluffy, written-for-tropes, quick-and-fun fantasy romance.
No one's survival is guaranteed except the endgame romance, which you might or might not discover in this book. At the end of this book, one of her potential loves will die, one's survival is debatable, and one will live to torment her... Don't say I didn't warn you. And, yes, she is going to get mad. (But not till the third book lol)This is also not YA. Despite the heroine being 16 at the beginning of this book, she ages up as the series progresses till she's in her 30s.