A Dead Horse Trope now. Up until the 1960s onwards a common story was to have Bob, a White man, or Alice, a White woman, in Darkest Africa
, Qurac, the Wild West
, or the Far East
, fall in love with a non-White person. The different races would be an obstacle to their happiness until it was discovered that the other partner was actually White.
The operetta The Bohemian Girl.