Dear XX,

        I am excessively sorry to say/tell you that XXX.(直接表达自己不能实现先前的愿望或约定) Now,I am writing you this letter of apology to show my deep regret XXXXX.(表达歉意) Please accept my sincere apology XXXXX.(诚恳希望对方能接受道歉) I fear you are displeased at XXXXXX(表达出自己的心情，并请求对方原谅). I hope you will understand me and excuse me for XXXX(总结出自己道歉的原因). Therefore it's not in my power to XXX.(希望下次再次实现愿望)

       Naturally,I want to suggest XXXX. I shall be obliged if you will kindly write and tell me when and where you XXXX.We may meet again and I hope to See you soon.(约定下次约会的时间地点)。

                                                                                                              Yours sincerely,

                                                                                                                  Li Ming