Simply replace the unfilled areas such as "" and "[date]" with your information.
You have asked me again and again to forgive you. No matter how hard I have tried, I simply cannot. When you [action], you didn't just let me down, you broke my heart. Even now, there are times when I look at you and I can still feel the pieces shattering inside.
The blame does not rest solely on you. Perhaps I held you to standards that were too high, some kind of pedestal. Perhaps I simply fooled myself into believing you were the kind of [woman/man] I wanted you to be, without really seeing who you were. It really doesn't matter any more, because I can't continue on with you.
They say that when a heart breaks it comes back to love more deeply. That may be so, but that love won't be for you. I am sorry, but I have to say goodbye.