Thanks for the read and the feedback Kwame :)
I wouldn't classify this as a mistake - but it was certainly a learning moment for all of us involved.
There were definitely preconceived expectations, but it wasn't because of a lack of communication. We spent over 9 months constantly communicating and discussing boundaries, limits, and expectations before ever getting involved sexually with another couple.
What we were unprepared for was the way our bodies would react to being with other people.
After nearly 15 years together, we assumed being with another like-minded and attractive couple would turn us both on, and were both surprised when it didn't.
The good news is we're still very close with the other couple and we're all still exploring the lifestyle.