A Conduit of Light (Conduit of Light Trilogy #1) by Chelsey Tompkins:
 
Twenty-year-old Ash’Arah is forced from her home as payment for the cure that healed her city. She will train to become a conduit, wielding magic for the good of the isle in Felgren Forest, led by the very man who took her. She refuses to go quietly, however, taking every opportunity to show Baron Heimlen that she does not intend to stay, no matter how powerful her magic appears to be. But when a closely guarded secret is revealed, she cannot deny her role as the forest’s savior any longer, nor her newly ignited passion for Heimlen’s successor, Baron Revich.

Karus is a woman who wanders the forest in an endless string of days until she discovers a stone embedded in a fallen tree. Holding it, memories of her past awaken, and she is forced to confront what her heart has tried to hide and the secrets withheld from her.

And as the fate of the forest falls into question, these women must face the truth of who they are, who they are destined to become, and who they love before they are consumed by the weight of what they have been chosen to bear.