Q. A Rov teaches a shiur in a Yeshiva and lost his father and is still within the year of Avelus. One of his close disciples is  getting married in the near future and he feels that it is very important for him to be at the wedding and show how much he cares. Is he allowed to go, while he is still an Avel?
A. In principle he could just attend the Chupa and leave before the music and dancing begin. (See Shulchan Aruch Y.D. 391:3. Gesher Hachaim permits after Shloshim).
Horav Dovid Pam Shlit’a mentioned that he can also attend the Chosson’s Tish and be a witness or read the Tenoim, if at that time there is no music.
Rabbi A. Bartfeld as advised by Horav Dovid Pam Shlit’a