Great question. What would I have done differently? If I were doing it over again, how would I have given WH space to do his own work without also rug-sweeping?
Thinking about my own experience in hindsight, I think reconciliation requires both your compassion for her process and clear evidence that she is taking responsibility. The key is not to "step back" in a way that minimizes the betrayal, but to create a structure where she has space to do the work while you keep firm boundaries and watch for consistent accountability.
Her healing is her job, but rebuilding trust is your joint job. You can give her room to work on herself without pretending the affair is a closed chapter. (and maybe your MC needs to hear that message, too). This keeps the focus on repair, not punishment (of her), and it avoids the trap of making your comfort the only standard (which is what would cause her to say "I can't win").
Stepping back:
Stepping back can mean reducing control, not reducing standards. Give her space for reflection while still expecting high standards for honesty, consistency, and follow-through. You can't manage her personal growth, but you can observe whether she is genuinely engaged in it. While this is a judgment call, does she seem to be doing the uncomfortable work on herself or just saying the right things to stabilize the relationship? You'll likely get a better feel for this over time. My biggest mistake - and what I'd do differently now - was confusing control and standards. I let both go down and ended up complicit in rug-sweeping for 12 years.
You also can ask for specific evidence of change. For example, is she in IC and going consistently? Is she able to name her triggers and defenses honestly? Is she consistent over time in showing you green flags like taking full responsibility, tolerating painful conversations without defensiveness. And do you see fewer red flags over time, such as blame-shifting, rushing you to forgive, or using her shame as a substitute for repair?
Rug sweeping:
I see rug sweeping as trying to move on without naming the harm, understanding the patterns, or making concrete change. A way to avoid the rug-sweeping trap can be to say "I'm willing to give you space to do your work, but I'm not willing to pretend the affair didn't happen. I need to see active repair, honesty, and consistent change if we're going to reconcile." Sounds like you've already said this, but I mention it because I didn't do this in my R, and that was a huge mistake. You also could say "I respect that you have a need to sort out your own patterns, and I need a relationship that feels safe. If I don't see accountability and sustained change, I can't keep investing in R." That frames your safety as a legitimate requirement, not a threat.
I would not look for perfection but for trajectory. If she's moving toward honesty, accountability, and deeper self-awareness, R has a foundation. If you observe her mostly trying to escape guilt or discomfort, then you're attempting to rebuild on sand. And all of this takes time, so you might also think about how much time you're willing to give before you seriously assess trajectory. It's not reasonable or fair to either one of you to be measuring constantly. But would you give it a month before you take a step back and assess? Three months? Six months? You might reduce the angst you're feeling by giving yourself permission to let the process roll for a bit - whatever timeline you feel is acceptable - before you judge her progress and your feelings.
Hopefully there is a nugget or two in here that is helpful to you.