Can the whole truth be told in a relationship..?

For the sake of being trusted, couples try as much as possible to be transparent. However, the unanswered question remains if partners can ever be fully open and tell the whole truth in their affairs.
Beyonce and Jay-Z have been in  a long term relationship. Net Photo.
Beyonce and Jay-Z have been in a long term relationship. Net Photo.
Susan Babijja