I think when its good we'll just know, and it will take time, alot of time. For me it would be after sufficient time had past and the wife had through her actions, and priorities indicated I am the number one man in her life and that she does not have enough time to contribute to any more affairs or anything else going against the marriage. That nearly in every facet of life that they are thinking about their marriage as a priority, in their actions and interactions. I believe after sufficient time has past where the relationship partner has put the relationship as number one, that the pain of the past will eventually fall off. Kinda like bad credit on a credit report.
So it may be after 2 or 3 years of good, things are pretty good and after 7 years of good they may be pristine, that the pain of the past would be a small and distant memory.