I'm glad things are working out for you. My husband and I opened up our marriage when I was 50 and he was 48. We were having a grand time together and were in a highly exploratory phase, so invited other people to join just seemed like the next thing to try. Then I met someone that I loved, and we had to do a little adjusting because that wasn't the original plan, but we got through it and are both happier and more in love with each other than ever.
A big part of that is due to what you described - unhooking from the roles and societal expectations of what it means to be a husband and a wife. I feel more like an individual now who has intimate connections with other people, one of whom is my husband.
I may have mentioned this before but about 2/3 of marriages that open up do so at the request of the woman. Obviously, the guy needs to really be on board with it too and it's better when it's not done to "fix" something in the relationship. That being said, I'm glad that it's going so well for the two of you.