Because that’s one of the facets of the whole “cuckold” genre,,,of the five or six major facets of this genre, that’s in the top three! Black or White, a Bull dealing with a cuckold husband draws a good deal of pleasure from pleasing the wife in front of the husband, displaying how he’s more superior in that task, it goes without saying, claiming the husbands pussy in front of him by cumming inside it, and quite possibly impregnating it, is also highly desirable for the same reasons, humiliating the husband, and taking possession of what’s his,,,extra points if the wife openly agrees with the Bull,,,especially in front of the husband. After that, next step is employing the hub in also serving the Bull,,,”and the beat goes on”,,,