Rule's Bride (Bride Trilogy) - Kat Martin

Unrepentant rake Rule Dewar is living the good life when a most surprising event occurs—he falls in love with his wife.
After their strategic "marriage of commerce" three years ago, Rule quite forgot about Violet Griffin, the teenage heiress to a Boston manufacturing fortune. He simply spoke his vows, took over her father's business and returned to England to resume his usual pursuits: high-priced wine, high-stakes gambling and highborn women.

Yet when Violet, now a sophisticated woman, unexpectedly appears at Rule's London town house, husbandly duties no longer seem so odious—he can't wait to take his stunning bride to their marriage bed. Violet, however, is not so easily led: she has her own ideas and is seeking an annulment to marry another. But as Rule attempts to win her over, someone else is determined to frame him for murder and keep him out of the way for good….