Is it permissible for the wife to look at her husband's phone conversations, and is it permissible for the husband to grant her permission to do so?

A man may permit his wife to view his conversations if they do not contain secrets of others who might not wish for anyone to see them, for a conversation is a trust, and spying on it is forbidden by Islamic law. As for the wife, it is not permissible for her to view her husband's conversations with others without his permission, and his silence does not count as permission. The advice is that neither spouse should view the other's private conversations with others, out of respect for privacy and to avoid mischief.