The Billionaire Needs a Life by Rachael Eliker

They’ve loathed each other for as long as they can remember. When they have to fake love, their feelings might not be as pretended as they supposed.
Gemma’s focus is on her professional ambitions because it’s what she can control. Success has already cost her a personal life, but she’s so close to securing a merger that’ll make her a billionaire that the sacrifice seems small. Whatever it takes, she’ll make it happen, including faking an engagement to her childhood enemy.
It would have been easy for Fletcher to call Gemma crazy when she introduces him as her fiancé, but there’s something to be gained from the ruse. Gemma isn’t the only one who would benefit from a pretended relationship.
Calling in his favor, Gemma and Fletcher have to convince his family for a week that they’re madly in love, then they can go their separate ways. The only problem? When it’s over, they might realize they don’t want the feelings to end.