Ok yah I see your point and concede. Either way MJ came off as the better person in this story, no doubt. But I'm pulling for Peter to come around, realize he was wrong and get back with MJ and restore his family life.
I was calculating and this book seems to take place at or around year 7 in their marriage. Thats a time when alot of marriages fail. Its long enough that the initial thrill of being together is over and alot of things settle in for the long haul. Just smacks many people broadside and they panic and decide to bail.