The Rake's Rainbow [Three Best Friends Series Book 1]

Caroline Cummings, a talented vicar's daughter, is inadvertently compromised by Thomas Mannering, rake and second son of an earl. They are forced to marry, though Thomas is obsessed with a now-married London beauty. While Caroline works to understand her tormented husband and build a life with him, he struggles to maintain his honor and their social position in Regency society. Regency Romance by Allison Lane; originally published by Signet and winner of Romantic Times Best First Regency award for 1996.