From a woman's perspective...(in a marriage of 22 years that has invited black guys off and on over the years)
Do you know why Black Guys turns her on? Skin color, body type, something different, being naughty, the excitement of it all, cock size? Start with emphasizing those things into your dialogue.
1. What's really holding her back? You, her, the *******?
2. Maybe she only does it because it turns YOU on so much...and that turns her on?
3. Maybe it makes her feel guilty when she wants to Skype/chat on her own? (feels like she's cheating)
4. Maybe she's not comfortable showing emotion and passion towards another person with you around. Until she can be comfortable with your reactions to her reactions, this will never be a pleasurable experience for her.
5. Are you pushing her too fast? Going slow is the best thing...and be careful not to slam on the brakes when she wants to go a bit further than you.
6. If you are not completely trusting of eachother and understand eachother's expectations, then this sort of lifestyle can drive you apart pretty quickly.
OK. Nuff said. Hope this helps.
Natalia