Devil's blessing

One day, right before Christmas...
A shady guy shows up out of nowhere and tells the main character, "I'll grant you three wishes."
Thinking it's ridiculous, the main character ignores him, but then her first wish comes true anyway, almost against her will...
After that, there's a junior at work who suddenly turned cold toward her.
Plus that same shady guy who calls himself a demon.
Which hand will she take?