Shakespeare’s sonnets are a remarkable collection of poems and their essential theme is that of love.
This particular sonnet stresses the constancy of true love: It is not fickle or changing, but is constant and true:

Sonnet 116

Let me not to the marriage of true minds
Admit impediments. 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,
That looks on tempests, and is never shaken;
It is the star to every wand’ring bark,
Whose worth’s unknown, although his height be taken.
Love’s not Time’s fool, though rosy lips and cheeks
Within his bending sickle’s compass come ;
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 prov’d,I never writ, nor no man ever lov’d. - Sonnet 116

Love which is here today but gone tomorrow is not real. There is a difference between like and love. Our likes and dislikes tend to change rather quickly. Love, as spoken of in the sonnet, is constant. It does not alter when it meets some problem or difficulty.

Notes based on Arden edition of Shakespeare's sonnets:

We hope you have enjoyed the above excerpt. If you are interested in reading further sonnets and other works from William Shakespeare many of them are generously published online by www.shakespeare-online.com