If you are confused in your thoughts and feelings, you could do the work to un-confuse.
WHAT is confusing?
To experience desire for another? That's normal. Doesn't mean you have to do anything about it either. Just because one marries, doesn't mean one stops crushing or noticing when other attractive people go by. You are not dead. (But you do have marriage agreements to uphold.)
Is it something ELSE that is confusing?
What could that be? Are you able to articulate it? Do not move forward without sorting out what is so confusing first.
If you and spouse are thinking/talking about changing your agreements to shift toward an open marriage? READ. Lots.
Esp what kind of open model
you are after and how you'd cope with potential Pitfalls and jealousy:
Try it on just in the safety of your heads and hearts alone together. Before trying it on mind, heart, body and soul with others.
If you cannot talk about all that NOW when nothing is going on in a sane way, you def don't want to be doing it in crisis.
Here's more links:
I am sure other people have other good links and books.
That said -- there's nothing wrong with wanting a poly or mono shape relationship. You two could figure out WHAT it is you want together and HOW to go about achieving it in a good way. Or research it and come to find "Nah. Not for us after all" but have grown closer for the experience anyway.