Iamjack, I think the real answer here is that you are "staying together" but are not truly "reconciled".
People who are reconciled may have triggers or setbacks, but it appears that you are simply are both simply "white knuckling", which means you are both holding on for dear life, so hard that your knuckles have turned white.
But that ain't the same as reconciliation.
I am willing to accept, as my therapist tells me, that she was another person at the time of the adultery.
When it comes to cheating, therapists are frequently full of platitudes that they use to try and comfort people, seemingly to "move them along" to a "healthy place".
First of all, she was not a "different person". She was a different person with him, because she wanted to do whatever she was doing with him, and she wanted to do whatever she did or didn't do with you.
Yes, yes, new relationships and all that, but put away this idea that she was some other fake person. She really was/is the person who had all the motivation to happily and willingly do what she did with him.
And it sounds like you in your heart of hearts, and in your mind as well, you can't really swallow that, no matter how many junk explanations your therapist or your wife try to sell you.
You say you are happily married and reconciled.
If your best friend told you they felt that way about their wife and marriage all the time, would you consider that friend to be happily married? Would you consider him or her to be reconciled?
Now let me take it a step further. What if you expressed the way you feel to her, the things that you wish she would do, and she started doing those things for you - that she did for him, presumably without him asking? Would it be good enough for you? For her to have to be told to do those things for you that she willingly did for him?
I am going to guess, no it would not be good enough. I am guessing it would not relieve your burden.
Frankly, from what you wrote, this is eating at you constantly. I know the feeling. It's miserable.
Like somebody else wrote above, you are allowed to walk away.
I would suggest that if you are not ready to call it quits outright, then take some time away from her to see how you really feel. Just be in your own life, without a therapist - or your wife - trying to explain away her shitty behavior.
Sometimes shitty behavior is just that - shitty behavior. You are not required to accept half-assed love from your wife. Take some time for yourself and see if you really want to continue with her.