The Oath by Jillian Bondarchuk

He’s the chieftain of Clan MacKinnon; she’s the daughter of a powerful druid. When they are forced through magic into an arranged marriage, will it end in war… or passionate surrender?
Bound by a blood oath that feels like a curse, Malcolm MacKinnon quickly regrets the promise he’d made to Vanora, the witch who would save his brother’s life: protect her daughter… or die trying. He needs to collect her before the marsh violets bloom, but as winter thaws, Malcolm hesitates to fulfill his vow… and time is running out.
Living on the fringe of her people, shunned because of the scars that mar her body, Coira always knew she’d die a spinster. But when a stranger arrives with an outrageous—and unenthusiastic—declaration that she’s now under his protection, gratitude is the furthest thing from her mind. Torn from the only home she’s ever known, and surrounded by the superstitious inhabitants of Ghlas Thur, Coira feels more isolated than ever before.
Passions and prejudices clash, magic balances life and death, and both must choose between holding on to guilt and past injustices, or embracing the happiness they both deserve.