You think the whole cafeteria noticed you eating alone. Most of them were worried about their own table.

The feeling of being watched is almost always louder than the watching. Everybody there is running their own audit: who to sit with, what they said in third period, whether somebody is annoyed with them. You are a passing detail in about forty separate stories, each of which is mostly about somebody else.

Test it instead of arguing with it. Try to name three people you noticed yesterday at lunch and what they were doing. The blank you draw is the same blank they drew about you, and it is a freeing thing to confirm.