My guess is that the betrayer will be back in contact with the affair partner, or some other source of validation, when they have to sit alone with their own feelings.
I also think that the betrayer is still in survival mode, and hasn’t yet started to mourn the loss of their other relationship, and why that was important to them.
I think. The betrayed person will find that hard.
My advice to the betrayed person is that the chill, unfraught feeling you will experience on holiday can be yours all the time. The worry that the relationship is good “for the moment” but knowing a bolt can strike at any time will not be there. You can choose to live without that background worry. You can choose to live without having to monitor your spouse for signs that they maybe unhappy, when you know that unhappiness equates to “entitled to cheat” for them.
Three years down the line I am so so glad that I took the bull by the horns on day 1. All the “I love you”s were lies really, yes to me, but also to themselves. They loved the nice easy life they had off my mental load, but beyond my utility as white goods, no they didn’t.
What’s really interesting though is since I have started dating again I have definitely discovered that cheats don’t love their partner, you cannot love someone you don’t respect. Cheats don’t respect their spouse enough not to do the dirty on them. Kicking a cheater instantly into touch is an action that demands respect, and that’s why it is the best action to take. If they want to rebuild, then they can start from scratch.