It Happened at Christmas by Sandra Sookoo

A widow needing attachment. An earl searching for hope. A young girl wanting a family. A handful of days to change everything…

Lady Lydia Kingston has pretended for years; it was easier that way. As headmistress and owner of a finishing school in London, people trusted her because they thought she was a proper woman of the ton, except all of that was a lie, but when her sordid past collides with the present she’s worked to build, scandal follows and sends her to Scotland despite the imminent holiday season. No longer does she believe in that magic.
Jackson Ramsay, the Earl of Greystone, has no patience for what the season demands. London lost its polish and draw, neither is he in the mood for revelry or festivities and he certainly doesn’t want a woman to complicate everything. Spending the holidays with his daughter brings difficult memories, and not wanting her to be exposed to the emptiness that is the beau monde, he takes her on a holiday to his estate near the Scottish Highlands. The joy of Christmastide has long been forgotten.
Misfortune throws the earl and Lydia together, but the forced proximity of a shared road trip sparks a strong attraction between them, and a yearning for more. In the Lake District, a fierce snowstorm strands them; necessity has the three essentially playing house until the roads clear. Desire consumes the couple, but her secrets and his might just destroy the love they both desperately need and deserve before unexpected traditions can be born.

… showing that magic and miracles can happen on Christmas if they only believe.