How can you have a feeling for who your true self is when you have no one to be your true self around?

You are with your friend or friends. You have fun. But you don’t entirely feel you’re being your true self. Though you may like your friends it still leaves you disappointed.

How do you know you aren’t already being your true self? How do you know there is more you’re not revealing? In what ways would you change if you found someone to be your true self around?

If you have found someone to be your true self around, then compare you’re self to people you aren’t your true self around. How do you change?

This isn’t a question for myself, but a general question I am curious about.
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You have not found that person yet, say. Is there really a way for you to know how you would behave around that theoretical person?
How can you have a feeling for who your true self is when you have no one to be your true self around?
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