Angel Off Limits by Veronica Conley

A guardian angel sworn to protect. A woman with a troubled mind. He’ll protect her at any cost, but what if the cost is her sanity?
Coralyn’s guardian angel is never going to let her down. But Cora is unlike any mortal the angel Arathiel has ever guarded. Death shadows her, demons chase her, and even the higher-ups in the Greater Angels of the Empyrean are watching.
What’s worse is that Arathiel can’t hide from Coralyn. She can see her guardian angel even when she doesn’t want to. As supernatural danger draws near, Arathiel is always by her side, and Cora struggles with a deep fear about what it means that she can see a man no one else can. As Arathiel’s connection to Cora grows stronger, he faces a dilemma. For him to protect her, she must believe in angels, but he can never give her the thing she needs the most: the truth that he exists.
Cora’s survival depends on her ability to trust in something she cannot prove. But is her faith in Arathiel strong enough to save her life?