The feelings for me is a mixture (like both their cum) of humiliation, being obedient and controlled, and mostly on my part, a show of loyalty and approval of the entire situation. You have to figure this as a definite. When you not only taste another mans cum but also accept it inside your own body, then you become a small part of that man. Much the same way a female feels when a man cums in her, there is a special bond made between them right then and there.
For the males though, when one provides the cum and the other tastes and accepts it inside him, the provider owns the accepter. Why? Mainly because that establishes and then states sexual dominance and control. The black man uses the white boys own wife to obtain his own sexual satisfaction and release and then hubby has to taste the results of that satisfaction and release as a performance with an audience. His wife is sexually content, so is the black man all while hubby is still carrying his own cum inside his loaded set of balls and then must humiliatingly taste the black cum result of his wife and the black mans sexual gratification.
There is also an added twist of humiliation that the white boy feels from it after the fact and as an end result. He knows that he did something that the black man has never and would never do, yet the black man watched him do it. The black man gains an ego and self esteem boost from it while the white boy gains...neither one. He does gain sort of a sense of accomplishment though. Much like the black mans feeling of accomplishment but in a totally different way.
The white boy can go out into his normal society and be around his normal surroundings of people and places with a feeling that he has did something possibly that no one else in this room has ever done. But who knows, he just might very well be in the same room with others that feel the same way and are holding the same secret and feelings as a result.