How loosely or strictly do they use the word ‘friend’?
Phoebe uses the word friend very loosely, but only with entirely selfish intentions. She has learned how to gain people's trust, turning on the charm that makes people feel safe around her. They feel safe with her, more willing they are to let secrets slip.
She will make "friends" as an alibi, or use someone to get close to a target. She keeps drinking buddies at different taverns, mostly to stave off the appearance of being a "suspicious character" that would draw attention from locals. Are any of them real friends? Never. They may believe it but she will never let any of them see who she really is. Her faith in anyone knowing beyond the surface character she plays has been burned to the ground. She knows the only person she can ever trust is herself only.
Now, it's not impossible to be her friend... just very nearly. It would take something absolutely impressive to even start to gain her trust. Until that happens though, she will keep up her defenses so that no one can have an advantage over her.
@unabashedrebel thank you for sending this in and patiently waiting for me to answer! Really enjoyed this question, lets me dip into her very dark and cold personality that hides under so many layers, that it's hard to be found.