The husband perhaps is afraid of being thought of as a perv for bringing the subject up, The wife will usually wonder WHY he wants to do this, perhaps having a feeling of inferiority, not being enough woman to satisfy the hub in the usual ways..Sex outside of marriage is still somewhat looked down upon in our society even if both partners are willing to try it.. Another reason may be simply finding a third who is compatible and makes both the hub and wife feel comfortable taking this big of a step. There is much more to this than jumping in the sack with some BBC picked up at the corner tavern.=p
I believe that if the husband were to prove that this is really is what he wants and it will only strengthen the relationship it would happen more often. How can he prove it? By working harder on doing things around the house that she normally does but she does not enjoy doing them. This is done after she has been blacked. Every time after she has been blacked.
This gives her a visual reward of seeing him take over these chores plus the rest she receives from not having to do them herself. And all that on top of her being freshly satisfied sexually by the black guy.
The black guy wins because he got some from a white wife.
The white wife wins because she most likely had the best sex of her life and now feels satisfied sexually. Plus she is seeing a change in her husband, not of jealousy, but of support by doing the little extra things now that she used to have to take care of herself.
The white husband doesn't win quite as much as the other two but he does get to see what he wanted even though he is now having to work harder to receive less. If he is not willing to do that for her then he should never even mention anything to his wife about any part of it. It would be the husbands responsibility to make sure that any feelings of regret that the wife may have are quickly put to rest by him showing her that it's okay by spending time with her and doing what she wants to do.
It's up to him to keep the wheels of a good marriage rolling and again, if he is too squirrely or wishy washy that it ends up affecting him too then leave it alone.