If it wasn't for the presence of big black men I wouldn't have a cuckold bone in my body! But when they are around there's something about them that brings out the beta male in me and the accompanying desire to be a cuckold.
There it is!! When my wife views a hung black man in porn my anxiety level goes through the roof because I know she is thinking about how big he is and wondering what he would be like as a lover. It is unsettling to know she is thinking that but there is something about her seeing a black man and wanting him that brings out the beta male in me too.
As you said, black men come from outside our "tribe", middle class white america, so I accept the fact my wife responds to black men in the manner she does and I get why she would be interested in black men sexually.