Dear [their name],
By now, you must realize that I am gone, and that I am not coming back.
Don't feel responsible-it's not you, it's me. My [ busy career / expensive drug habit / intense racquetball schedule / fascination with on-line pornography ] prevents me from committing to a serious relationship.
Besides, you deserve better. You deserve someone who appreciates all of your most special qualities, especially the cute way you [ leave your toenail clippings on the couch / sing along when you don't know the lyrics / feign naivete when I suggest you do laundry / scarf down two pints of Ben & Jerry's while watching Ally McBeal reruns ].
Even though we're no longer together, we'll always have our memories. I'll never forget the time you [ asked me to pull your finger / made me lie about my religion to your parents / brought home a bucket of KFC on my birthday ]!
They say that time heals all wounds, and I hope that soon you will be able to [ love again / like again / speak my name without sobbing / speak coherently to another person of the opposite gender ]. When this time comes, I hope that we will be [ good friends / fake phony superficial friends / in different states / as far apart as humanly possible ].
Love Always, / Love, / Warm regards, / Fondly, / Adios,