Nova Book 3 of Katiah Trilogy

Loving Brehan is enough to push any Guardian over the edge, and Erth is close to plunging into an abyss of regret from which there seems no escape.
Since he can't bring himself to destroy the woman he loves, he creates a series of schemes to confuse their enemies and test the strength of Brehan's human side. It only creates a wider emotional chasm between them.
Understanding that love has brought her nothing but pain and grief in the past, Erth offers up a supreme sacrifice to tear down the walls between them and to win her heart.