The theme of attraction between opposite types of people is a frequent theme in Diana Palmer books. Often characters have conflicting professions or backgrounds. Her books also center an older hero/younger heroine trope.
In the book "Hunter", a man with Native American roots begins a romance with a geologist. In this book, the sacred earth concept conflicts with the scientific sensibilities of the geologist. In "The Morcai Battalion: Invictus," a battle commander falls in love with a field medic.
Her books "Sweet Enemy," "Diamond Spur" and "To Have and To Hold" all feature a more mature male falling in love with a younger woman.