Why do some women always blame their husbands having on the other woman & not their husband?

Do they not know that it is very likely their husband lied to the other woman about being married in the first place? I mean come on! Nobody really condones cheating. Im not saying this is the case all the time, but the majortiy of them time it is. Even if the other woman was to know, why is it her responsibillity to uphold two other persons wedding vows? Women always blame the other woman & not the husband & i think its pathetic b/c the husband actually owes the wife something. The other woman doesnt owe the wife a damn thing. I have noticed that some women will take more crap from their husbands then they will their own mothers & sisters. I have heard of lots of women not even listening to their own KIDS when the kid complains that their dad is molesting them. The women do not even believe the child & sticks with the husband, half the time not even investigating the allegations. Why is this? I think all of this is very sad.