This Laird of Mine by Gerri Russell

Claire Elliot has two weeks to win the heart of Jules MacIntyre—and then break it. To save her wards from a vicious blackmailer, she dares to enter the laird’s castle, claiming to be the wife he’d recently wed. But no such wife exists!
The brooding Jules invented a bride to silence his well-meaning, matchmaking friends, so he never expected her to arrive on his doorstep. He is suspicious of this beautiful stranger, but he’s also steadfast, courageous, and effortlessly seductive. In fact, he’s the very man Claire would choose to love…if she weren’t forced to betray him.
She is an intruder at best, and a liar at worst, but still Claire enthralls Jules like no woman before. He agrees to let her stay—at least until he uncovers the truth—and soon she is filling his manor and scarred heart with the warmth they have both been lacking.

While an unknown enemy has chosen Claire as a weapon to destroy the laird, Jules vows to fight for the passion he has found with his fantasy bride made flesh.