A Perfect Engagement by Karla Kratovil

When Charlotte Grisham is saved from an out-of-control carriage by a handsome gentleman, she knows fate has sent her the perfect man. The Marquis of Hawksridge is titled, handsome, and heroic—precisely the kind of gentleman her parents want for her husband. Before Charlotte knows it, she is engaged to be married.
Daniel Weston can’t believe his identical twin brother is marrying a lady he barely knows. Moreover, he’s begging off his own engagement party. Daniel allows his twin to talk him into going to the week-long house party in his stead…just for a few days. They used to pretend to be each other all the time in their youth. What could possibly go wrong?
Charlotte immediately realizes her fiancé has sent in a doppelgänger, but continues the ruse so no one will realize her fiancé has all but abandoned her. Everyone sees her as perfectly behaved. But perfect girls do not share searing kisses with men who are not their betrothed. Charlotte knows her duty, but what about her heart?