Mae Meets The Highlander Niall by Rebecca Preston

Transported across centuries by a mysterious fae magic, Mae finds herself on a run in the wild Scottish Highlands — and find the man that helped her escape.

When Mae Welles, a psychiatrist looking to reform from her past, finds herself thrust into the past, she encounters Niall, archer of Clan Donald. His good nature slowly wins her over as they host a stranger to the Clan.
But as ancient magic entwines their fates, Mae and Niall must confront the unwelcomed guest. Will they be able to endure their differences against those against them?