In think in some cases it isn't fear (although that can be the case) as much as a deep dependancy on these men. Very often the wives really believe they love these men or that they can't live without him. They are so dependant that they choose the husband over the child. Sometimes they don't believe it even when the husband admits it!!!
My mother was the type to say that a woman can't live without a man so she wound up living with the dregs (3 men who all sexually abused children). She really believed she could not survive on her own. So she always put the men before the children.
Now that she is alone she still believes she can't survive alone so her new "love" is the WTS.
And the last time I talked to her about husbands and marriage she still said I needed a "good" man to take care of me!!!!
Last time I checked I do much better on my own - without either a man or the WTS