His Christmas Wife by Sierra Cartwright

It will take a Christmas miracle for this Scrooge of a boss to convince her to be his wife.

To appease his marriage-minded grandmother, Billionaire Evan Frost needs a make-believe wife for the holidays. Only one woman possesses the poise and polish to fulfill the role, his assistant, Kaylee Robbins. There’s just one problem. She loathes him.
Months ago, when Frost blazed into the CEO’s office and ruthlessly fired half the company, Kaylee couldn’t afford to quit in solidarity. Now, at a holiday party, the bastard demands she pretend they’re married during his family visit this Christmas. She’d refuse, but the bosshole uses her dire financial situation and his wealth to coax exactly what he wants.
But over their holiday, she sees a different side of Evan and surrenders to his commanding presence. When her innate warmth thaws the ice around his heart, he becomes determined to make her his forever and spend a lifetime proving himself worthy of her love.