If your going to eat out with the whole office, please do not leave one intern behind

I am currently sitting at my desk, alone in the office. I wasn't aware there was a lunch at the restaurant planned for the leave of one of the interns (he arrived two months ago). Suddenly everyone one gets up and leaves. Everyone passed in front of me, no one acknowledged my existence. This intern was there for two months, I'm there since April. It hurts, not only for the obvious rejection but also for the meaning behind it. Fuck that