I'm the last one to tell anyone else how to live their life - even if this post sounds like it. To me, it's the age old keep it in your bedroom.
For the last few years or maybe even decades it just seems like people who practice open marriages are trying to make it mainstream. But it's not and never will be. 92% of open marriages fail - likely because they try it as a last ditch effort to save their marriage, instead of entering into from the beginning as you and your partner did.
If you want to live that way - more power to you. I choose to live forever single, which is probably also a sexual anomaly. I just don't love coming across those who are ENM trying to sell me on the idea or acting like it's a viable way to save a failing marriage.