Romance between humans and devil angels? That's a specific mash-up, and frankly most books get one side wrong. The devil or demon is just a bad boy with horns, and the angel is a self-righteous bore. But 'Daughter of Smoke and Bone' by Laini Taylor comes close—the chimera are basically demon-adjacent, and the seraphim are angelic, with a human caught in between. It's messy, beautiful, and the power imbalance feels real, not just edgy.
I'd also throw in 'Angelfall' by Susan Ee. Post-apocalyptic, angels are the villains, and the human girl has to partner with one. The romance is a brutal, slow-burn thing born out of necessity and mutual hatred. It's less about celestial beauty and more about survival, which makes the connection hit harder.
Honestly, I'm still looking for a book where the 'devil' isn't secretly a tortured softie. Give me a proper, terrifying Adversary who falls for a human anyway, consequences be damned.