To my mind, cyber cheating is just as bad as the real thing...It can even lead to the real thing.
My friend's marriage was destroyed by her husband's insistence on practising this past-time, even though he never actually got together with the 'other woman'. His persistence and habitual 'addiction' of this behaviour caused his wife to reach the verge of a nervous brakdown.
He refused to see it as cheating or being disrespectful, and didn't consider that it damaged his wife's dignity or self-respect. But he did agree that from the moment he began 'cyber-f***ing' as he put it - the physical relationship he'd had with my friend disappeared.
He put this down to the fact that she no longer did anything for him....
This may be an extreme example, but it's all I got.