This line of thought is completely unreasonable BUT I know why a woman would adopt these ideas:
Thinking this way removes all blame from the husband, and she can go on thinking he's the sun, the moon, and the stars. If she accepted that he was a cheater, she'd have to be angry with him.
And thinking this way removes all blame from herself. It wasn't that she failed to keep him interested, failed to notice what he was up to, put other things ahead of him, etc.
And it puts the blame solidly on an outsider. An evil woman -- all sorts of names are available for her. If the other woman is the target of the spurned wife's anger, then she doesn't have to accept that anything's wrong within her own family.
Note: I'm not saying that this line of thought is acceptable or correct in any way. But I do understand the idea of pushing blame on the wrong person to avoid pain.
I can see that ..I don't know if he has cheated on her or not ...but what I do know is that both of their older kids that are out of the house will not have anything to do with at all..they grew up with this mentality and they had to wear long dresses, no make up and made to believe the man was god period, plus he moved them out to the boonies..now to make this clear they were NOT pentecostal or anything..I never met his family so i don't know what they are like..I also know that they tell everyone they met at church when they really met at a bar ..I found this out by accident, my cousin and I were talking and it was mentioned that they met at a bar and she said no they met at church and I said my parents said they met at a bar ...so my cousin ask my gma and she said no they met at a bar ...I felt bad but you know that's what happens when you lie..

I think they are in some fantasy world or something??