Does Hollywood Avoid Black-White Interracial Couples?

In "The Skin Game" Stephen Cole suggests that Denzel Washington has had a career plagued with starring alongside white female co-stars but, in every role, Denzel has never pursued a romantic relationship with them.

This is an interesting observation.  The author continues that Hispanics and blacks seem to be fine in Hollywood.

There appears to be no taboo against black superstars romancing Hispanic starlets. Actress Eva Mendes was allowed to play with Washington's heart in Training Day and Out of Time, then date Smith in Hitch. Rosario Dawson, meanwhile, won the hearts of Smith and Eddie Murphy back to back in the 2002 films Men in Black II and The Adventures of Pluto Nash.

In The Pelican Brief, Denzel and Julia Roberts starred opposite each other but never had any hint of a romantic relationship, even though such a relationship was present in the book.

Does Hollywood remove the presence of interracial black-and-white couples to sell more tickets? 

Denzel refused to kiss his Kelly Lynch, his white co-star in Virtuosity:

During an interview in Jet magazine, Lynch later suggested she had no trouble with the scene, "but Denzel felt strongly that white males, who were the target audience of this movie, would not want him to kiss a white woman."

 I would also like to add that black females, who are big fans of Denzel's work, may also not like to see Denzel kiss a white actress.  Regardless of the reasons, it still seems that Black Hollywood A-list actors are seldom seen in romantic relationships with White Hollywood A-list actresses.

Is the underlying theme here that blacks and whites shouldn't be romantically involved?