I am not referring here to a marriage that breaks up because a mother discovers her husband has been abusing their daughter. They might be.
Abusers are to blame.
Child sex abuse traumatises children in a way which may dominate the whole of their lives, affecting all their relationships, especially sexual ones, affecting self esteem, self image, self worth and future marriage, making future sexual difficulties far more likely. Those who abuse children for their own sexual gratification are rightly regarded as social deviants, criminals against which there are sanctions in a civilised society. Yet many child abusers were abused themselves. Thus an act of sexual abuse can have a knock on effect, carried down through generations of neglect, abuse, suffering, despair. I am not justifying sex abuse or making light of it in any way just because an abuser may previously have been a victim of abuse.