Untouchable. Midheaven, #1

Some choices have eternal consequences. Sam Gregory is a Watcher, a human-angel hybrid built for eternity and hell-bent on avenging his father's murder. He's given up earthly distractions to hunt the fallen angel responsible, so when he crosses paths with Chloe Thibodeaux and discovers her empathic powers coupled with an intense attraction, he fears she's the bait in an ancient prophecy involving them both. Sam must now discern between free will and predestination.
If he makes the wrong choice, literal hell on earth breaks loose. If he makes the right choice, he and Chloe ride into the sunset and the world will never know how close they came to losing everything. Making the right choice sounds simple, until the woman you've fallen in love with might die in the process, and the only thing you want is her.