Lady Macbeth, Macbeth's "dearest partner of greatness" (I.v.12) has a drive and determination which would threaten most people and, indeed her husband. She is less affected by the setting at the beginning and it is more opportunity that creates tension for her. However, as soon as she hears of Duncan's imminent arrival, she is plotting and scheming "the fatal entrance of Duncan." The setting then becomes very relevant and does increase her confidence and so create some tension as Duncan will arrive "upon my battlements,"(36)- her home.
The audience sees Lady Macbeth's self-assurance when she takes control after Duncan's death and returns the daggers. Similarly,after Banquo's death, Macbeth is haunted by his ghost and, even though they are now in the palace at Forres, it is her domain as his Queen. She is able to allay the fears of guests when Macbeth is delusional, confirming that "the fit is momentary."(III.iv.55) Lady Macbeth takes in in her stride.
As Lady Macbeth loses hold over Macbeth, she becomes increasingly affected. Although, she is still in her home, she is affected by her diminishing control over the situation. She cannot even "wash away" the imaginary "spot." A strong-willed, self-possessed person like Lady Macbeth can no longer cope in a setting where she is not controlling everything and the tension is enhanced, ultimately signalling her demise as she descends into madness.