In Shakespeare's Macbeth, the only person in the play Macbeth is open with is Lady Macbeth, but he is extremely open with her until after their plan works and after the revelation to Lady Macbeth that her husband has killed the grooms.
Macbeth is not afraid to tell her anything. Upon his return from killing Duncan, he tells her he was unable to join in on an overheard prayer by saying "Amen," he tells her he heard voices, he tells her he can't handle the blood on his hands. In short, he is not afraid to show weakness and shortcomings in front of her.
He is also open with Lady Macbeth during their first scene together after he is named Thane of Cawdor and predicted to be king. They're both aware that Duncan is on his way to their castle to spend the night, and they both know what that means--an opportunity to assassinate him and claim the throne. They are affectionate and endearing.
Of course, any openness ends soon after the successful assassination. Macbeth does not consult her before ordering the deaths of Banquo, Fleance, and Macduff's family. At one point he excuses her from his presence so he can be alone. We barely see Lady Macbeth for most of the play, and when we do she is either berating Macbeth for being stupid, or suffering from her own guilt.
The relationship that was once open, is closed for most of the play.
I would not describe Macbeth's exhibition of his feelings and emotions as open-ness, rather as the dis-inhibition sometimes associated with mental disorders and the unravelling of the mind. Indeeed, in the play 'Macbeth' by William Shakespeare, we see in the witches scene, the suggestion of further ambition for Macbeth being taken in, hidden and internalized by Macbeth. He does not even share his true opinions on the bloodthirsty idea with his friend, but seems already ashamed or secretive about them. Later on, of course, he soliloquizes about them, and even mentions them where others could hear - causing Lady Macbeth anxiety over possible discovery. By the end of the play, he is shouting his head off about his plans above the roar of battle - and his ambitions are 'open season' for all.