Macbeth said "Remember to pay special attention to Banquo. Show him favor with your looks and words. We're still not safe, and so we must make our honor look clean by washing it in streams of flattery. We must make our faces masks for our hearts, disguising what our hearts are."
Together they don't decide anything. Macbeth alone decides to kill Banquo, he does not tell Lady Macbeth of his plans.
Banquo won't even be at the party because the murders would have killed him by then
No, Lady Macbeth is not aware that Macbeth has planned the death of Banquo and Fleance.
Macbeth does not reveal his plan to kill Banquo and Fleance (Banquo's son) to Lady Macbeth.
MacBeth meets the three witches with lady MacBeth
Macbeth wrote Lady Macbeth a letter describing his encounter with the witches. Lady Macbeth reads it out at the beginning of Act I Scene 5
A major character trait of Macbeth and Lady Macbeth is that (to a certain extent) they regret the murders of Duncan, Banquo, etc. It eventually drives them into madness
No, Lady Macbeth is not aware that Macbeth has planned the death of Banquo and Fleance.
Macbeth does not reveal his plan to kill Banquo and Fleance (Banquo's son) to Lady Macbeth.
Lady Macbeth begins to sleepwalk after murdering Banquo.
Macbeth Lady Macbeth Banquo Fleance Malcolm Donalbain Macduff Lady Macduff
Lady Macbeth was also missing from the banquet table in the scene from Shakespeare's "Macbeth" where Banquo's ghost appears. Lady Macbeth excuses herself from the table, fainting in response to Macbeth's behavior and the appearance of Banquo's ghost.
MacBeth meets the three witches with lady MacBeth
In both cases, the ghost that appears in Macbeth is summoned by the guilt and inner turmoil of Macbeth himself. The ghost of Banquo is a manifestation of Macbeth's guilt over his role in Banquo's murder, while the ghost of Lady Macbeth represents his guilt over her death and his descent into madness.
Macbeth wrote Lady Macbeth a letter describing his encounter with the witches. Lady Macbeth reads it out at the beginning of Act I Scene 5
A major character trait of Macbeth and Lady Macbeth is that (to a certain extent) they regret the murders of Duncan, Banquo, etc. It eventually drives them into madness
The difference is that Lady Macbeth at first wanted Macbeth to kill Banquo and Macbeth was too scared to do it. Later on in the tragedy, Lady Macbeth gets haunted and gets mentally ill and Macbeth keeps on killing people.
Lady Macbeth is not involved in the plan to kill Banquo because the decision to murder Banquo is made by Macbeth alone. Macbeth wants to keep Lady Macbeth out of this particular act of violence to protect her from its consequences and to shield her from the guilt associated with the murder of their former friend. Additionally, Macbeth wants to keep the full extent of his plans hidden from Lady Macbeth to prevent her from being implicated or becoming a target of suspicion.
Lady Macbeth wasn't in on her husband's plans to kill Banquo. When she asked what his plans 'of dreadful note' [Act 3 Scene 2 Line 44] were, he didn't want her to know the specifics. But most likely yes, she would have wanted Macbeth to kill Banquo. Earlier in their conversation, she commented that Banquo and his son Fleance were mortal [and therefore killable?].