The Trouble with Love and Ink by Harriet Ashford

Emily Lane is supposed to be on vacation. Instead, she’s in a meeting where a new hire steals the promotion she’s been slotted for. To make matters worse, the promotion thief is a bit of a jerk both inside and outside cubicle walls.
Needing an escape, Emily takes on her sister’s dare to work for her calligraphy company. After all, Emily has been perfecting her pointed pen skills for over a decade. The only caveat: she will have to pretend she’s her sister while finishing the projects for a high-profile client’s wedding.
It’s all going according to plan until Emily discovers the client’s brother is none other than Beckett—Beck—Atteridge, office jerk and promotion thief. He will keep her true identity a secret on one condition: she has to be his fake date for the wedding in Costa Rica.

As lines are blurred between what’s fake and reality, this vacation will either be the escape Emily’s been looking for or a heartbreak she doesn’t need.