Must be nice to be so talented & in-demand that you can turn down white pussy simply because of some silly rule.
Personally, I can't see any drama in this whatsoever. What it is, is getting all the concerns out regarding this kind of relationship before being with the married woman with some level of expectations and then being disappointed because they had a different understanding of the event.
If you, for example, do not wish the husband to be present when you have sex with the wife you should mention it in the discussion with them along with the fact that everyone involved has been checked for social diseases. These would be "your conditions" and much respected, I might add.
Actually, working with married couples would benefit you most as you wouldn't have to worry about an irate husband suddenly showing up because his wife was really cheating on him, and the chances of social diseases would be less seeing as the couple is married.
I sense you simply have some negative feelings regarding the white husbands. Just remember YOU are the added 3rd party, you are the invited guest into their lives, plus they bare more overall risks. I would imagine they would be a bit apprehensive the first couple of times.
Or, maybe it is that you simply don't like living/fucking white women under some format of RULES. Is THAT IT? A lot of married couples have high respect for their marriage.
I imagine that once you've been with a couple a few times you will have gained their trust/respect and they would then be willing to relax the rules for you. Maybe you could send a "thank you" note to them afterwards to express how you enjoyed the evening with them. Nothing like building/earning a little "respect". Right? Or do you feel "entitled to respect" without earning it?