There's something very primal and animalistic about a bigger stronger male taking the wife or gf of a weaker smaller man. The female choosing the more dominant male equates humans with many polygynous animals where the rules of the jungle apply. The smaller male is emasculated while the bigger more dominant male is emboldened with testosterone pumping through his veins.
Now add to the 'rules of the jungle' scenario the fact that the smaller male and his partner are white and the conquering male is a dominant alpha black male and you've got an added electric interracial element to an already powder keg of primal ******* sexuality.
The 'cruelty' of this situation is compounded for the white male by the fact that his white wife or gf may give birth to a black baby, confirming to the world he's been cuckolded by a black man and she has chosen to mate with a black man over him. There's no hding from this, as is possible in a vanilla cuckold situation.
Historically this may have been one of the ultimate fears for white men but out of this has grown a fetish/eroticism whereby some white males actually want to enact and play out this fantasy. Being the weaker white beta male who is powerless to see his darling white wife/gf lust after and be taken by bigger more dominant hung black alpha males enables him to vicariously experience what a smaller real white cuckold must feel, but in this case the angst is transformed into sexual eroticism and elation.
I wonder if this applies to any white cucks and wannabes here, it certainly won't for many but I think it may be relevant in the mind of this cuck wannabe - poor bugger!