The Rogue's Redemption - The Leighton Sisters, #1

Haunted by war and his own dissolute behavior, Gerrit Hawkes finds no peace in postwar 1815 London. While the rest of society celebrates the British victory over Napoleon at Waterloo, Gerrit seeks to escape the memories that haunt him. Into his life steps Hester Leighton, from the Maine Territory across the ocean. Despite his warnings, Hester puts her trust in him. She refuses to see the evil and darkness he keeps telling her is in him.
Knowing he needs the Redeemer's love, she offers him the gift of friendship. When her father takes her back home, Gerrit must face the prospect of remaining in London and completing the self-destruction he's begun, or leaving all his familiar moorings and following the only woman who offers him hope.