Her Outcast Scot. The Highland Warrior Chronicles, #5

A warrior haunted by his cursed past... Pledged to protect dark secrets that could destroy his family's honor, Ross MacIntosh cannot afford to lose his heart. Sent by his king into Pictland, he knows his duty. To report back on any signs of treachery. He might not trust his king but as a warrior his fealty is absolute, and his path is clear. But when he's attacked and left for dead, he awakes to discover his healer is the intriguing Pictish princess, Orabel, and his carefully planned future unravels. A healer princess forbidden to love by her goddess... After enduring an arranged marriage to a brutal Northumbrian warlord, Orabel wants nothing more to do with politics.
Now, she will follow her true destiny and pledge her life to her beloved goddess. But when fate thrusts Scots warrior Ross MacIntosh into her life, her conviction falters. How can she feel anything but contempt for a man whose king is responsible for the death of her royal father?  A political marriage that could shatter everything they cherish... Compelled to wed to prevent bloodshed blighting their land, trust is a fragile illusion.
But with a vengeful goddess demanding restitution, Ross will need more than Orabel's healing skills to mend the rift that threatens to tear her from his arms forever.