In Your Arms Again by Kathryn Smith

Since North Ryland and Octavia March were wrenched apart and their childhood friendship destroyed, much has changed. North has had a successful career as a Bow Street runner, and has made quite a name and fortune for himself. So much so that when Octavia’s fiancé (for she is now engaged to one of the most desirable men of the town) needs to hire a man to investigate threats on Octavia’s safety, he is the only man that will do.