The Enemy Contract by Jason Collins

AVERY:
Faking a relationship with Hunter Westbrook should be easy—if only I didn’t hate him.
When a scandalous tell-all threatens to expose both of our families’ secrets, I’m forced into an uneasy alliance with Hunter—gorgeous, arrogant, and maddeningly impossible.
We’re supposed to work together, but every conversation turns into a battle, and neither of us is willing to back down. Until his mother, the infamous Betsy, hatches a wild plan: fake a romance with Hunter, fool the press, and save our families’ reputations. Simple, right?
Except the Westbrooks are worth six hundred million dollars, and I’m a high school teacher barely scraping by. Hunter and I have nothing in common—aside from the undeniable pull that, against all logic, keeps drawing me back to him.
But the longer we fake it, the harder it is to remember it’s all just an act.

HUNTER:
I have no interest in playing nice with an Ashford, least of all Avery.
Sure, he’s easy on the eyes. But he’s also frustratingly stubborn and entirely too good at getting under my skin. When Betsy’s fake romance scheme becomes the key to saving our family name and a multimillion-dollar deal, I have no choice but to play along.
But I need Avery. And for this plan to work, we have to convince everyone—including ourselves—that we’re falling for each other.
The problem? Somewhere between the staged kisses and forced proximity, hate turns to something else. Something I have no business craving.
This is all for show. A performance. A lie.
But every lingering look, every accidental touch, burns hotter than it should.

This is the second book in the Westbrook series. It can be read as a standalone with no cliffhanger.