Polyamory has been getting a lot of press.
It basically means having concurrent relationships with more than one person.
You might have one primary but everyone you choose to be with is more or less equal in your affections.
My preferred configuration isn’t actually that radical: ethical non-monogamy is basically a good old-fashioned open relationship.
There would only ever be two of us in it but I’d like to trust that person so implicitly and value them so wholeheartedly that if they slept with someone else it wouldn’t damage us.
I’d like for the other person to trust and value me just as much so that if I did the same we’d be able to look at it for what it is: a banal act that is fun or weird or intimate or exciting but ultimately not a threat to our harmony.