Shakespeare on the fickle nature of earthly love

Merchant of Venice

Act II Scene VI

Salerio

O! Ten times faster Venus' pigeons fly
To Seal love's bond new-made, than they are wont
To keep obliged faith unforfeit.

A Midsummer Night's Dream

Act I Scene I

Helena

Love looks not with eyes, but with the mind,
And therefore is winged Cupid painted blind.
Nor hath Love's mind of any judgement taste;
Wings, no eyes, figure unheedy haste:
And therefore is Love said to be a child,
Because in choice he is so oft beguiled.
As waggish boys in game themselves forswear,
So the boy Love is perjured everywhere.