Our Open Marriage, But Only Same Sex

My husband and I had an open relationship when we were dating. It continued after we got married, though it quickly transformed into same sex. Alone, I'm almost exclusively only sexual with women, and he almost exclusively is only sexual with men. Mostly we are sexual with our large group of friends, so it's a mostly closed circle..mostly, but not totally. When we are together, we both swing both ways, but the majority of the time, it's opposite sex. We talked very little about it before hand, but often talk about it now.

Has anyone else developed this dynamic or anything similar?