Tomte by Jamie Fessenden

RYAN ANDERSON has known something was wrong since he was a teenager. He’s been tormented by a sense of emptiness and loss—but what did he lose? He has no idea. Then a mysterious man appears, calling himself Tomte, a Swedish word Ryan remembers hearing from his grandmother in his childhood.
It means “Christmas elf.”
With the help of his older brother and his nine-year-old niece, Ryan begins a journey to discover what happened fifteen years ago, when he disappeared during a winter storm and didn’t reappear until spring. Not only has he forgotten those months, he’s forgotten the faithful dog who failed to come back with him.
As memories surface and impossible things happen all around him, Ryan senses Tomte, that beautiful man he’s inexplicably drawn to, is the key to everything—his past, his future, and his happiness.