The Heat of Christmas by Max Walker

Maverick Gold and Theodore Perez are a newly-minted couple experiencing all the thrills of a new relationship, heightened by the magic infused in the holiday season.
It’s a season Theo doesn’t always look forward to, but this year change is in the air. Theo is invited to a holiday party being thrown by Stonewall Investigations that promised a murder mystery mixed with tons of Christmas cheer.
He decides to go and brings Maverick with him. There, they find that one of them has been assigned as the Secret Santa Slayer and so the hunt begins. Maverick and Theo have a shot at figuring it out, they just need to keep their hands off each other for longer than three minutes at a time.
…They might need a Christmas miracle after all.