Is this weird?

For a long while I've know that the idea of watching my boyfriend be with someone else really turns me on. However recently he and I talked about it and I came to the conclusion that one person that really turns me on thinking about him being with is my best friend. We actually got intimate today to me telling him to do whatever to me that he would do to her and it was good. But I'm not sure if this is normal? Anyone else have weird fetishes like this?