Void of Endings by Hillary Raymer

In a war to save all they love, the tides of fate are not in their favor.
After an encounter with the memory keeper, Maeve is determined to protect Faeven. Though the task isn’t hers alone, she’s crushed beneath a burden of guilt, one that pushes her away from everyone, including Tiernan. When a reckless decision throws her directly into harm’s way, the fate of Faeven is set in motion, and this time, it’s all her fault.

The sacrifices will be great, the lives lost will be many.
With their battle plans foiled, Tiernan is forced to move quickly, relying on two unlikely allies. One betrayed Maeve’s loyalty, the other betrayed her heart. Unfortunately, there’s no guarantee his plea for help will be answered. Despite the odds stacked against him, Tiernan is certain of one thing. Maeve must survive, no matter the cost.