Seems to me that the true tipping point will be if/when she says "I want to commit to our M. What do I need to do?" Until then, I just need to detach and give her the opportunity to miss me.
It almost seems to me like she's trying to get back into the marriage and the family, incrementally, WITHOUT having to commit to it -- or to you. Kind of a "Hey, can we just forget all this happened?" sorta thing. While simultaneously maybe doing a "hey, we need to cool it for awhile" thing with OM as opposed to a full break there either.
It shows a lack of introspection and having "done the work," as we've discussed before (and therefore a recipe for failure), but it does seem like that's what she's trying to do, at least to me anyway.