Originally Posted by Banjo

I'm aware of that, but it's still a violation of the vows. A vow is a solemn promise. Even if the couple get married knowing they'll share each other with multiple partners, it's still deceptive.

Lying is something that is frowned upon by the society, it's even illegal to lie in some situations and you can get sent to jail for it.

I don't think people really realize how dangerous the concept of deception is.