Macbeth portrays love and marriage in the traditional sense. You marry someone in order to advance in society. Yet “Sonnet 116” shows us a different kind of love, where people love for love’s sake, and don’t expect anything but love in return.
In “Sonnet 116” the speaker expresses a view of love without obligation. He explains that love is loving no matter what.
Love is not love
Which alters when it alteration finds,
Or bends with the remover to remove:
O no! it is an ever-fixed mark (Shakespeare-online.com)
In this version of love, rank and what you can get from marriage does not matter. Macbeth, on the other hand, portrays a woman whose only interest in her husband is to advance through him. She does not care what he wants. She wants to be queen, so she convinces him to kill the king so he can take his place.
In Macbeth, love is loyalty. Before he knows he is not chosen as Duncan’s successor, Macbeth profusely vows affection for King Duncan.
Your highness’ part
Is to receive our duties, and our duties
Are to your throne and state, children and servants,
Which do but what they should, by doing every thing
Safe toward your love and honor.(30) (Act 1, Scene 4, p. 7)
Duncan also reciprocates this love when addressing Macbeth.
The love that follows us sometime is our trouble,
Which still we thank as love. (Act 1, Scene 6, p. 21)
Macbeth again expresses love for Duncan in explaining why he killed the supposed suspects (whom he framed) in a fit of rage and “violent love” (p. 36).
There are actually very few other references to love in the play. Macbeth does address his wife as “my dearest love” when he first returns to the castle, but it is merely a term of endearment and not really an expression of affection. Lady Macbeth uses the word in much the same way when she scoffs at Macbeth.
From this time
Such I account thy love. Art thou afeard
To be the same in thine own act and valor
As thou art in desire? (Act 1, Scene 7, p. 23)
They do not appear to be an affectionate or particularly amorous couple. It seems that they had children, because Lady Macbeth talks about nursing. She says she loved the child in one breath and would be prepared to bash its brains out in another.
I have given suck, and know(60)
How tender ’tis to love the babe that milks me:
I would, while it was smiling in my face,
Have pluck'd my nipple from his boneless gums,
And dash'd the brains out… (Act 1, Scene 7, p. 24)
On the other hand, the speaker in Sonnet “116” is not so fickle with his love.
Love alters not with his brief hours and weeks,
But bears it out even to the edge of doom.
If this be error and upon me proved,
I never writ, nor no man ever loved. (Shakespeare-online.com)
For him, love is eternal. It is not love until you are no longer needed. You do not throw love away for no reason.
When Lady Macbeth dies, her husband seems only momentarily affected. They clearly do not have the passionate love found in the poem. For them, love is mere practicality. It refers to loyalty, and nothing more.