I.
Tell me not, (sweet,) I am unkinde,
That from the nunnerie
Of thy chaste breast and quiet minde
To warre and armes I flie.

II.
True: a new Mistresse now I chase,
The first foe in the field;
And with a stronger faith imbrace
A sword, a horse, a shield.

III.
Yet this inconstancy is such,
As you too shall adore;
I could not love thee, dear, so much,
Lov'd I not Honour more.

Richard Lovelace

http://www.poemhunter.com/poem/to-lucasta-going-to-the-warres/