She warns Ivy to be on her best behavior. If she isn’t careful she just might find herself on the outside looking in.

What does 'on the outside looking in' mean here?

Thank you in advance.
She is presently "on the inside," or, an accepted member of the group. If she continues her present behavior, she may become ostrasized, or no longer welcomed as a member.

My mother used to say, "I'd rather be on the outside looking in, than on the inside looking out," possibly an allusion to being in jail. (which my mother was not)
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Hi Avangi, thank you for your explanation. What do you mean by 'on the inside'? Does it mean 'in the building'?
It could be a building, or it could be figurative. You might be a member of a gang which does not allow its members to quit. My use in quotes was figurative, meaning you're accepted, or have "inside" knowledge of something which "outsiders" don't know about.
I get it now! Avangi, thanks a lot.
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