Down on One Knee by Sage Kingsley

Sebastian Hale has a problem. He needs his inheritance to pay for his brother’s cancer treatment, but thanks to a clause in his parents’ will, he won’t be able to access it unless he gets married before he turns 30.
And his birthday is less than a month away.

His solution? Ask his tall, tattooed, and sexy-as-hell best friend, Rook, to marry him. Sebastian doesn’t do relationships, as a rule: he’s certain he has nothing to offer a romantic partner, and if there’s any simmering tension between him and Rook, he’s been doing just fine ignoring it so far. After a year of marriage, Sebastian will inherit, they’ll get divorced, and no one—including Sebastian’s meddling relatives—will be the wiser.

Cameron Rook has a problem. He’s been in love with his slender, snarky, sharp-tongued best friend, Sebastian, for as long as he can remember. But the one time Rook tried to confess, Sebastian shot him down. Hard.
At least that’s how Rook remembers it.

So when Sebastian asks Rook to marry him just for show—and offers a generous amount of money as compensation—it’s the last thing Rook expected. But he would do anything for Sebastian. Even when living in close quarters only fans the flames of the irresistible pull between them, and Rook is in serious danger of falling into Sebastian’s bed… After all, there’s no way this can go wrong. Right?