Of Ashes and Wildflowers by Erin Fae

Princess Naria has always preferred crafting medicines to wearing tiaras. Living in a secluded forest village, she studies healing after a huge fire destroyed her kingdom eighteen years ago. But when a gilded carriage arrives, her people rejoice while she reaches for her anxiety powder. The time has come for Naria to rejoin royal society and rebuild her fallen kingdom as a queen.
However, even her heaviest science books seem simple compared to life at the palace. Worse still, she’s being forced to marry the roguish Prince Lukas, who declares that Naria’s only use is to bear him heirs and that her kingdom should remain in ruins.
Determined to escape her engagement, Naria spends her nights sneaking away to the crystal-walled, underground realm of the faeries. Yet, while the faery prince might be willing to help her people, behind his charming looks lies a sinister obsession for his darling new princess. To deepen her troubles, the more Naria finds herself in heated exchanges with Lukas, the more she begins to fear she’s falling for the wrong prince.