Re: Her BF says: “I have a friend that’s a girl…”
To answer your question…
I think she has to a right to be weary, although she has male friends, she isn’t emotionally close with them. The bf and his female friend probably have a close emotional friendship. Especially if they usually talk from time to time and he hasn’t told her about them being bf/gf. Now I don’t think this will lead to cheating, especially if the relationship is good. But if that girl tries to pursue her bf, it might lead to something. If there relationship isn’t on the up and up. Anyways all of this is kind of conjecture but still.
Him not telling his friend about his gf is kind of unsettling, I always tell my friend of who i’m talking to, she does the same with me. I would assume he’s probably keeping her as a plan b. But tbh, it could be that she just got over a bad breakup and doesn’t want to tell her that he’s been dating someone?
If I was her, I would keep things status quo until she has more info, of course ask why he hasn’t told her and see what BS reason he gives.