I'm sorry you are in a place of "suckage".
It seems to me like you opened up your marriage with the idea that you would both explore and your wife has found those explorations fruitful and you have not had as positive of an experience.
You are not alone. In my brief months here I have heard a number of stories where wives have had an easier time finding new partners than their husbands have. (In this arena, it seems as though women are at an advantage.)
I don't have any great wisdom to add. If you were single, instead of married and poly, I STILL wouldn't have any great wisdom to add.
Here is what you have:
1.) You have a wife who loves you. Yes, she has other obligations/constraints on her time. Don't we all! Whether it is kids or jobs or whatever. Think of all the lousy, unhappy marriages you have seen - are you, deep down, glad that you have something so much more special than that?
2.) You have the freedom to pursue any opportunity that might arise with someone you are interested in (it might not work out, but you can rest in the knowledge that you are NOT a cheater, you are NOT a bad person, you are NOT abdicating any of your agreements).
It took me 19 years to run into someone that was worth the work that poly requires. (Granted, I wasn't actually "looking"...) My advice (such that it is) - enjoy what you have, pursue activities that interest you, cultivate friendships with interesting people withOUT being invested in the outcome...you may be surprised by who shows up in your life unexpectedly.
Me: poly bi female, in an "open-but-not-looking" Vee-plus with -
MrS: hetero polyflexible male, live-in husband (22+ yrs)
Dude: hetero poly male, live-in boyfriend (3+ yrs) and MrS's best friend
Lotus: poly bi married female, "it's complicated" relationships with Dude/JaneQ/MrS (1+ years)
+ "others" = FBs, FWBs, lover-friends, platonic G/BFs, boytoys, etc.
My poly blogs here:
The Journey of JaneQSmythe
The Notebook of JaneQSmythe