A Witch in Time, by Constance Sayers

In the vein of Outlander or A Discovery of Witches, Sayers has made magic and time travel essential to the romance of a witch and a demon, who are doomed to repeat their tragic love affair over and over. In Belle Époque France, 1930s Hollywood, the desert of the 1970s, and present-day DC, Helen and Luke always find each other and always lose each other. But this time, Helen untangles the curse that has trapped her for more than 100 years and must commit an unspeakable act to finally break free.