We are not pieces of this puzzle.
Back to the topic of why last nite was so shitty. We hit a mostly Persian party first, then a Filipino/Mexican one. The reason that the parties were so shitty wasn't because I was of a different ethnicity, it was because some of my friends were of those same ethnicities, but they were at their highest level of discomfort. And when a large number of my entourage are uncomfortable, then that feeling diffuses to the rest of us.
If the party is mostly X ethnicity, then party patrons may prefer that it remain that way. If an X ethnicity person brings in a crew of non-X ethnicities, their "people" might scoff at them. "Why'd you bring those ppl here? How come you didn't bring in more X ppl? Are you not X enough?" So while that person's authenticity is being questioned, the non-X patrons are either ignored or having small talk with those who pity/admire their minority presence.
Note: this seems to only apply to parties with extremely high concentrations of a particular group(s). Diverse parties are a different story. And this situation seems to be very common within my group of friends. Whether we hit a White, Filipino, Indian, Korean, Persian, Viet, X party, somebody just won't quite fit in.