For a Scandalous Wager by Shannon Gilmore

If Evelyn Markham entertained any aspirations of escaping an unwanted betrothal contract without a fine, she’d have to do more than break a few rules. She’d need to set the ton on fire with gossip or be seen with a man whose name alone could cause a scandal. Dalton Rochester was just that man. From the moment she laid down a daring wager during a game of billiards, her fascination with the dashing rogue burgeoned into something heart-poundingly real.
The shilling Miss Markham surreptitiously slipped into Rochester’s pocket now lay snug in his boot, a constant reminder that even the tiniest pebble could feel like a boulder under the right circumstances. This was especially true when his best friend’s sister could send his pulse rioting with a look and his billiard stick missing on cue. When she whispered her challenge, “Make the shot, and I’ll make your day,” he found himself bewitched by the forbidden lady.
But now, he must steel himself against her charm because for the past three months, the little hoyden has been sending him notes requesting a private rendezvous. At this rate, his friendship with her brother, whom he owed a great deal, would not survive. Nor, with her persistence, would her virtue.

She started as a pebble in his shoe but quickly became his rock.