For the record, when I spoke of openness I didn't just mean in terms of sexual exploration. I was speaking in terms of your ideas about what you're willing to accept in a new partner and your thoughts about the shape things must take for you to find what you're looking for (a lifelong loving commitment from another person).
If your definition of "spouse" never in the past meant "someone who only ever has sex within the marriage", then changing it now to mean that seems to me to be a narrowing, or closing in. See what I'm saying? I agree that sexual freedom is far from the most important thing in life, the shift just puzzles me since it seems like you weren't in a place where you wanted to entirely cut off to other lovers until you realized that you were setting a double-standard. So, if it was never something you needed before, and don't need from each other now, why do you need it from the new person?
Understand, though, that I'm not trying to tell you that what you want or where you're at is wrong or bad -- I'm just exploring it along with you since, as you and others have commented, this sort of thing is so dang *interesting*.