Highland Wedding (Highland Brides 2) by Hannah Howell

The vivid scar that spans Sir Iain MacLagan's cheek is a daily reminder of the wife he lost - and of the enemy that still stalks him. Commanded by Scotland's king to remarry in order to unite two powerful clans, Iain reluctantly weds Islaen MacRoth, a woman whose delicate appearance belies a playful, seductive nature that proves dangerously attractive to a man who has vowed never to jeopardize his heart, or his loved ones, again...

Raised with eleven boisterous brothers, Islaen has little time for foolish romantic notions. Even so, she hoped for more than a forced marriage to a man who shares her bed, but not her life. Step by step, Islaen sets out to wear down Iain's defenses. But can her ruggedly handsome husband learn to give her his love freely as he bestows his passion?