For Love of a Laird by Mia Pride

She was a wonder of the world, and she was married to his brother.
Betrothed to the elderly laird of their enemy, disillusionment and duty are all Elizabeth Keith has ever known. She may never know true love, but her people will finally know peace.
However, when tragedy strikes more than once, and Elizabeth is pawned from laird to laird, unexpected desires for one man threaten to compromise her dutiful existence, forcing her to defy the rules.
As the spare to the heir, Robert Irvine understands his obligation to the clan during these volatile times. But, marrying his brother’s beautiful widow is more than he bargained for, and nothing he is prepared for. When all he never wanted becomes all he ever needed, Robert suddenly stands to lose it all.
When war is a constant threat, and a marriage to Elizabeth is the key to peace, Robert will do all he can to secure both, until he discovers she has done something that may destroy them both.