Well put, Toy.
For me the goal of a sex share is to share loving sex behaviors.
It isn't to orgasm. That's just a possible outcome.
Even with the same partner, each encounter will be different. Sometimes there's lots of orgasms, sometimes there isn't. Sometimes there's lots of time to indulge, sometimes there isn't.
I wonder if it's just natural that when my hormones start raging that it's instinct to want to be physical with my OSO since 1) it would be allowed and 2) She is available and willing and 3) It's super fun from a mental standpoint? and a little from physical.
Sure it is natural. And if it is also in keeping with your relationship agreements, and everyone is good... everyone is good then!
So this is really confusing for me. However I will continue to search within because I believe in questioning what a "relationship" and "marriage" truly means.
I think you could be questioning "desire" and "sexual expression" perhaps?
Because you are IN relationships with both your lovers already. One lover you also have a marriage union/contract/bond thing. My definitions run along the same at Toy's.
But let me add this and put it this way...
Sex share can be a part of a marriage. But a marriage is more than sex share.
Clam chowder is a kind of soup. Not all soups have to be clam chowder.
Your lovers are different people and touch different parts of you inside. You can enjoy them just as they are. They don't both have to be the same, or both have to touch the same places within, just because both are your lovers.