Farewell ungrateful traitor,
Farewell my perjured swain,
Let never injured creature
Believe a man again.
The pleasure of possessing
Surpasses all expressing,
But 'tis too short a blessing,
And love too long a pain.

'Tis easy to deceive us
In pity of your pain,
But when we love you leave us
To rail at you in vain.
Before we have descried it,
There is no bliss beside it,
But she that once has tried it
Will never love again.

The passion you pretended
Was only to obtain,
But when the charm is ended
The charmer you disdain.
Your love by ours we measure
Till we have lost our treasure,
But dying is a pleasure,
When living is a pain.

John Dryden

http://www.poemhunter.com/poem/farewell-ungrateful-traitor-2/