The Accidental Marriage by Nadia Lee

Having been kidnapped by his mother at age ten and left to die in a fire, billionaire lawyer Ares Huxley trusts no one. But he needs a wife to get a critical promotion at his law firm, and wakes up the morning after a friend’s bachelor party to find that he’s somehow married to an eccentric blonde he doesn’t even remember meeting!
He immediately plans to annul, but it turns out she needs a husband to receive her inheritance. They have nothing in common, but if he plays along, she promises to be his dream wife.
The rules are simple: Share the marital bed every night, no real feelings, and the marriage ends in six months when they both have what they want.
But living with this accidental wife doesn’t produce the respectfully indifferent marriage he envisioned. Despite her innocence, she’s feisty both in and out of bed. His family adores her, and when he learns that her family treats her badly, he finds himself wanting to protect her. And maybe more.
Ares can’t stop thinking about his unexpectedly adorable, irresistible, and wonderful fake wife. But despite his evolving intentions—and emotions—she abides by their fake marriage rules a little too well.

Ares realizes the one thing his wife wants from him is the one thing he can no longer do: Let her go.