I'm disappointed you forgot to bring any presents. 

你忘记带我的礼物，我好失望。

Are you disappointed very much?                                      

你很失望吗？

Talk to your friend when you're upset.                                

当你心烦时，告诉你的朋友。

If you're upset because of me, please tell me.

如果你因为我感觉到心烦，要告诉我。

Don't feel so bad. You can do better next time.                  

不要失望，下次你一定会做得更好。

Don't make me disappointed, please.

请不要让我失望。