向他道歉：
Hi, Eric, about yesterday, I must apologize to you. I am terribly sorry, I left without saying goodbye to you, because my friend called to tell me something urgent happened. I hope you can forgive me. It won't happen again, I promise. Next time if you need someone to show you around, please feel free to let me know. I won't let you down. Sorry again! May you a nice day~
以上内容,你可以根据需要挑有用的说,也可以给Eric发Email~
Good Luck~