Different Nationality Mob Wife
Tropes teach us that in civilian life the Nice Jewish Boy wants a Shiksa Goddess. An Asian Guy thinks blondes are better. And the black dude is infatuated with the white girl. Apparently these tropes apply heavily to the world of organized crime. It may be a latent desire to in some way escape the culture in which their criminality was bred. Maybe the girl is just hot. But the tendency in film and television for the wife or girlfriend of a character to be of an ethnic group different from their husband and/or his organization is quite prevalent.
- In The Godfather- Italian-American Michael Corleone, Kay Adams
- In Goodfellas- Irish-Italian Henry Hill, Jewish-American Karen Hill 
- In Scarface- Cuban Tony Montana, WASP Elvira Hancock
- In Carlito's Way- Puerto-Rican American Carlito Brigante, WASP Gail
- In American Gangster- black Frank Lucas, Puerto Rican Eva
- In Public Enemies- American Southerner John Dilinger, half-French half Indian Billie Frechette.
- In Pulp Fiction: black Marsellus Wallace, white Mia Wallace.
- In the series Boardwalk Empire- Irish-American James Darmody is married to Italian-American Angela, while friend Al Capone is married to an Irish woman.
Hello, Unknown Troper. You'll need to get known to lend a hand here.