Please understand that one of the reasons I have come to this decision is precisely that I want to preserve our friendship. Lately, I have begun to have concerns that the way things are going, this venture could potentially affect our long-term friendship. I fully expect that we may very well do business together again sometime in the future and I would also like to preserve the professional rapport and mutual respect and trust that we have established over the last five years. I have decided to seek an opportunity to learn the business from a different perspective but I sincerely hope to do so without any adverse effect on our friendship....

Above all, I wish to do so without changing our personal friendship and mutual trust in any way. Respectfully, and in the spirit of genuine friendship, I must withdraw from your employ although I do so with tremendously mixed feelings because of our friendship and the way you have always treated me. It is my sincerest hope that if I am ever in the position of employing others in my own business that I can be as good an employer and mentor to them as you have always been to me.
Your friend,