At the beginning of the play Macbeth and his wife are loving to each other: when Macbeth writes a letter to Lady Macbeth and calls her his dearest partner in greatness. This shows he sees her as his equal.
The breakdown of their relationship is caused by many things, the most obvious is the murder of King Duncan. Macbeth and Lady Macbeth react in very different ways: Macbeth is overwhelmed with guilt and regret Sleep no more: Macbeth has murdered sleep this shows how uncomfortable he feels with the crime he has committed as he wont be able to sleep because of the guilt he is experiencing. Lady Macbeth reacts completely opposite to Macbeth. She is calm and practical, telling him to wash his hands A little water clears us of this deed this shows how optimistic she is to think that water can wash away the guilt. Lady Macbeth takes control in their relationship as Macbeth is very weak and she questions his bravery and manhood, therefore they are no longer affectionate towards each other.
The mental suffering they both go through after the murder is another factor that contributes to the breakdown of their relationship. After being crowned King, Macbeth confesses he is discontented. To be thus is nothing, but to be safely thus. He has the idea that Banquo will become King and fears it will come true. At the same time, Lady Macbeth is feeling a similar disappointment: Nought had, alls spent when our desire is got without content. Yet the pair are not communicating at this point. Lady Macbeth has to ask her servant to tell Macbeth she wants to speak with him and he is plotting to have Banquo disposed of but keeps this information from her.