Is it time to let go of my girlfriend who is pulling away?

My girlfriend has been pulling away, acting cold and distant for the past ten days, and it's really bothering me. I tried talking to her once about it, but she shrugged it off.
Is it time to let her go, or is it too soon? I don't want to lose her, but it seems like I'm losing her slowly anyway.
I'm 100% sure but I think there's someone in the picture.
Is it time to let go of my girlfriend who is pulling away?
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