This is the #1 thing that people do wrong around here when they enter the reconciliation phase. They move too fast. As soon as their formerly-wayward spouse shows the slightest sign of wanting to work on things, they go all "melty-man" and start the pursuit again. Check out Futureunknown's latest thread for but one example.
To "stick," this phase has to be done verrrry slowly, and the formerly-betrayed spouse has to allow their formerly-wayward spouse to continue to pursue THEM. You need to convey an air of "I'm still not sure what I think," maintain all of your GAL things that you were doing when she was wayward, and let her earn her way back.