Thus with the vain thought
that she thinks me young,
Though she knows my days are past the best,
I just take the word from
her false-spoke tongue:
On both sides thus is plain
truth all down pressed.

But why is it she says not she's not just?
And why is it I say not that I'm old?
Oh, love's best guise is when we seem to trust,
And age in love loves not to have years told.

And so I lie with her and she with me,
And in our faults by lies we more vain be.

William Shakespeare

Let Me Not to the Marriage of True Minds 

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 wandering 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 proved,
I never writ, nor no man ever loved.