Feeling Santamental by M.J. O'Shea

Ellery Mitchell is a bit of a grinch... He's never been a big fan of the season, okay? Christmas is not exactly magical when it's dark and cold and his massive unrequited office crush still barely knows he's alive. So when Ellery's best friend puts his name in the Secret Santa pool she's in charge of, he thinks he might hate her forever... or at the very least for a couple of hours. But then something magical happens. Ellery's own Secret Santa leaves him a series of the sweetest, most thoughtful gifts... and notes. It's starting to look like Ellery's not the only one with an undercover crush.