This is the scene where Macbeth sees (or thinks he sees) the ghost of Banquo at the banquet table. Lady Macbeth asks his guests to leave and shepherds her husband out of the room, fearing that he will confess to the crime. This marks the final time that Macbeth is tormented by spirits, and it is the first time that Lady Macbeth is not able to chastise him into forgetting his conscience. His conscience, indeed, mostly disappears later in the play, as Lady Macbeth's worries her more and more. Macbeth decides that he will go and see the witches, and it seems that his wife will not play an important role in his life after this.
PS, sorry for all the grammer and spelling mistakes,
it is in act 3 that the audience see a clear change in the relationship between the macbeths.as the characters change the relationship between them changes.
Macbeth, who was acknowledged by king Duncan as a 'valiant cousen' and 'noble macbeth' (act 1, scene 2, lines 24 and 70) changed to someone that was described as an 'tyrant' as his reputation is in decline (act 3, scene 6, line 22).
lady macbeth however knew from the offset that she had to be the one that had to use the 'valour od my tongue' (act1, scene5, line 25) to persuade macbeth to comit the muder of Duncan. It is lady macbeth that remaind the leader of this murderouse duo untill act 3 where we she the change in their relationship.
because of the gult that Lady macbeth is feeling she being to weaken, we hear her first soliloque since the first murder;
'naught's had, all's spent,
where our desire is got without content.
'tis safer to be that which we destroy
than that destruction dwell in doubtful joy' (act 3, scene 2, lines 4-7)
it is shakespespeares use of a solioque and rhyming couplets that highlight to the audience how she is feeling.
only a few lines later do we see lady macbeth asking Macbeth for instructions 'what is to be done?' (act3, scene2, lines 44). because their relationship has become distant she doesn't know what macbeth is feeling or what he is planning so she is looking for guidance and comfort.
shakespeare shows the the change in the relationsip between macbeth and lady macbeth by the use of soliogues and rhyming couplets the highlight how they are feeling.
hope this helps.