I think you were almost there. Open communication is the key word for you. For any Indian woman it is important to make her come out of the shell / web of modesty she has built around her. Keeep trying I feel you will succeed
I dont think that any racial issues are involved as far as swinging is concerned. It is all about chemistry. I and my hubby were in the US three years back. We came across a young and a good looking American couple, who threw all kinds of hints to us to swap. Finally, the wife proposed to me in a very straight forward way. That time we were very possessive and had never even thought of swinging with another couple so we ignored it.