An Improper Marriage — Heather King

This book is a traditional Regency Romance with just a dash of spice.

When her stepfather suggests she should marry ironmaster Jeremiah Knight, Eleanor Honeybourne knows a lifetime of dullness awaits her, but at the annual glass-maker's ball, the discovery of an injured man in a summer-house and an overheard conversation lead her to suspect Mr. Knight is not all that he appears. With both her own and Robert's life at risk, Eleanor sees only one way out of the fix… and when she meets her childhood hero, she is forced into a situation which could well spell her ruin…
For Charles Ribblesford, meeting again the hoyden who once tagged behind him on his boyish adventures is a revelation. She is now a beautiful young woman who troubles him in an entirely different way. How can he preserve her reputation and keep her safe? What is the family secret behind Knight's malevolence and why has the man in the summer-house appeared at Sir Thomas Winningham's house party?

“I have nothing to say to you.”
“No? You do surprise me. I was quite sure you would wish to pull caps with me. I promise I will not dodge if you wish to throw pillows at me. I do draw the line, however, at any expensive vases or glassware.”