No more be griev’d at that which thou hast done:
Roses have thorns, and silver fountains mud:
Clouds and eclipses stain both moon and sun,
And loathsome canker lives in sweetest bud.
All men make faults, and even I in this,
Authorizing thy trespass with compare,
Myself corrupting, salving thy amiss,
Excusing thy sins more than thy sins are;
For to thy sensual fault I bring in sense;
Thy adverse party is thy advocate,
And ’gainst myself a lawful plea commence:
Such civil war is in my love and hate,
That I an accessary needs must be,
To that sweet thief which sourly robs from me.
In plain English
Stop being upset about what you've done. The world is full of flaws alongside beauty — roses have thorns, fountains get muddy, clouds block the sun and moon, and rot can eat the heart of a perfect flower. Everyone messes up, and I'm no exception.
But here's where I make it worse: I'm defending your wrongdoing by finding excuses for it. I'm corrupting myself in the process, patching over your mistake, making your sin sound less serious than it actually is. I'm even dressing up your betrayal in philosophical language to make it sound reasonable.
I've become your lawyer when I should be your judge. I'm at war with myself — loving you and hating what you did — and I can't help but become complicit. I'm helping the thief who's stealing from me, and doing it sweetly, bitterly aware of the trap I've set for myself.