I think Princess Diana said it best about when to leave a marriage: "Well, there were three of us in this marriage, so it was a bit crowded." This means if a man has a mistress, it becomes a crowded marriage. If a woman has an affair, it become a crowded marriage. If a man listens to his mother or friends, rather than his wife, it becomes a crowded marriage. If a woman listens to her mother or friends, rather than her husband, it becomes a crowded marriage. In a crowded marriage, one spouse has broken the vow to forsake all others. It is perfectly reasonable for the spouse who has suffered the pain of a breach of their sacred vows to reassess the relationship. It is perfectly reasonable for the spouse who has broken the vow to forsake all other to question whether they broke their vow to love, honor, and cherish. I think that this is the basis behind where you discern the difference between a character defect and a natural reaction to neglect. 

May you walk or sail in peace and beauty, Hozho, 

Gary