Oh, think not I am faithful to a vow! 
Faithless am I am save to love's self alone. 
Were you not lovely I would leave you now; 
After the feet of beauty fly my own. 
Were you not still my hunger's rarest food, 
And water ever to my wildest thirst, 
I would desert you--think not but I would!-- 
And seek another as I sought you first. 
But you are mobile as the veering air, 
And all your charms more changeful than the tide, 
Wherefore to be inconstant is no care: 
I have but to continue at your side. 
So wanton, light and false, my love, are you, 
I am most faithless when I most am true. 

Edna St. Vincent Millay
From A Few Figs From Thistles