I too hate disagreeing with ames, but as long as I’m with feivel I know that I’m not wrong.
You want to know whether or not it is derech eretz for a Rav to miss your simcha. And I responded that you have no business deciding whether or not what your Rav does is derech eretz. Actually, you have no business deciding whether or not what someone else does is derech eretz or not, unless you are the parent, rebbi (or rav) of that person and responsible for the person’s chinuch. As far as whether or not you have a right to expect a Rav to show up because you think it is derech eretz for him to do so, you do not have that right. It is for him to decide on his own.
Your statement:
Nevertheless, I feel that it a shortcoming in his middos to not show up
was despicable.