Girlfriend ignores me in public?

when we are alone indoors or out somewhere, we are inseparable. However, when we go to a public place with many people for example a party or a big dinner, she avoids me. it seems she talks to everyone else but doesn't spend even a minute with me. we have dated for 2 month and were close friends before that too. I feel ignored but I don't understand why. can anyone tell me why a girl would do that and be extremely close & affectionate when we're alone..? Please help. Thank you.
Girlfriend ignores me in public?
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