But firstly, another person told me that while the vegetarian said she did not mind, she really did.
It doesn't matter how she felt.
In life, there will always be people don't like what you do. And there will always be people who try to influence how you behave.
If you live and work in the United States (and from your other question, it does sound like you're in the US) you need to learn to be more assertive and stop caring about what others think of you.
By trying to control what others think of you, you are letting those other people control you. In other words, you're teaching others to treat you like a child, not an adult.
Also, I want you to notice the second question you asked about the private office a contractor claimed as his own. That second question stems from the same place this question comes from. You're a rule follower. You have a strong sense of fairness. You care too much about what others think of you. You put the wants of others above your own wants. You're a "nice" person.
But ultimately, this kind of personality won't serve you well in the United States. Over time, you'll grow resentful, bitter, and angry.