A Thousand Glittering Lights by Jennie Lynn Roberts

Only she can see him.
Ellie is about to release the hotly anticipated sequel to her groundbreaking romance-centred video game. But a horrible accident has shattered her confidence, her best friend is pulling away, and now a brooding man has started appearing in her cottage. Maybe he’s haunting her, maybe he’s a hallucination—he’s exactly what she would choose to imagine—or maybe he’s as real as he says he is… but he never stays.

All he knows is darkness… and Ellie.
He doesn’t remember his life or even his name, but he does know that he’ll fade eventually. He can’t stay in Ellie’s sunshine forever, despite their undeniable bond. But even her world has shadows; too many things have gone wrong for them all to be accidents. As his memories slowly grow, so does his fear that Ellie is in danger of losing everything she’s worked so hard to build—and more. And so does his realization that he’ll never stop craving her. And that there is nothing he wouldn’t do to protect her.

She believes in love. And he believes in her. Together, they could defeat death itself.