Shall I compare thee to a summer's day? (Shakespeare)
You're hot in spots and then you fade away....

Whoever loved who loved not at 'first' sight (Marlowe)
or even 'worst', depending on the light?

O my Luve's like a red, red rose (Burns)
And tu-lips lie beneath her nose!

How do I love thee? Let me count the ways. (E. B. Browning)
But years' own math subtracts your charms away!

Glenn Bagshaw

http://www.poemhunter.com/poem/famous-lines-from-love-poems-made-into-couplets/