Seeking the Fae - Daughter of Light, #1

Now that her mother is dead, twenty year old Lily is the last of her kind. A Seeker. Tasked with seeking the lost crystals of Faerie, she must restore her broken and barren world to its former glory. But the crystals that keep Faerie alive have been stolen by the Sons of Darkness and are hidden on Earth. It's up her to get them back by any means necessary. She has everything under control and plans to bring the first crystal back, when she meets Liam, a Son of Darkness.
He's the most dangerous kind, with black wings that smoke and eyes that have seen death. She must kill him, kill him and take the crystal, but she can't. He's her soulmate.