Vanished by Evangeline Anderson

Harper Wilde is sitting on the beach, minding her own business when a huge, muscular Kindred warrior with black hair and blazing white eyes demands that she accompany him into the future. Harper has no choice–she is dragged against her will into a dystopian nightmare–the world as it might become if something isn’t changed.
And that something that needs changing is Harper herself.

As a ten’sora, she is of special interest to the Hive, an insectile race of beings bent on taking over the Earth. By using her, they can conquer both the Mother Ship and the human race. Unless Harper is altered so the Hive cannot make use of her, the grim future she finds herself in will become reality.

Shad is a Shadow Twin–a Kindred male destined always to walk alone with very little chance of forming a bond with a female. Yet, he alone is able to make use of the looper–a time travel device which allows him to move back and forth between the past and the future to try and save Harper.
Falling in love with her isn’t part of the plan but the big Kindred can’t help himself. But he knows he must put his feelings aside and do what is necessary to change the past…unless he wants the future to Vanish forever.