tl;dr ... at least not the entire thread, but I want to give my meaningless 2 cents anyway ...
There arfe only 2 ways to deal with this:
1 - stay out of it and wait for the inevitable to happen before you think about making your move!
"But this isn't at all about me getting her" Yes it is - you just didn't admit it to yourself yet.
"I swear, it isn't" err ... what did I read in the op? ->a girl isn't sure about 'breaking up' with a guy (...) I really like her, and I don't like him.<-
"But we are just friends ..."
Harry: You realize of course that we could never be friends.
Sally: Why not?
Harry: What I'm saying is — and this is not a come-on in any way, shape or form — is that men and women can't be friends because the sex part always gets in the way.
Sally: That's not true. I have a number of men friends and there is no sex involved.
Harry: No you don't.
Sally: Yes I do.
Harry: No you don't.
Sally: Yes I do.
Harry: You only think you do.
Sally: You say I'm having sex with these men without my knowledge?
Harry: No, what I'm saying is they all want to have sex with you.
Sally: They do not.
Harry: Do too.
Sally: They do not.
Harry: Do too.
Sally: How do you know?
Harry: Because no man can be friends with a woman that he finds attractive. He always wants to have sex with her.
Sally: So you're saying that a man can be friends with a woman he finds unattractive?
Harry: No, you pretty much want to nail 'em too.
Sally: What if they don't want to have sex with you?
Harry: Doesn't matter because the sex thing is already out there so the friendship is ultimately doomed and that is the end of the story.
2 - Since you do want to get her (if you don't believe me, re-read this post), you will probably not stay out of it. And when this happens, under NO circumstances tell her to leave her boyfriend! Just tell her that in fact she already knows what she wants to do, and that all she needs to do now is admit it to herself and act accordingly. ... and then wait for the inevitable to happen before you think about making your move!
"But this isn't at all about me getting her" Yes it is - you just didn't admit it to yourself yet.
"I swear, it isn't" err ... what did I read in the op? ->a girl isn't sure about 'breaking up' with a guy (...) I really like her, and I don't like him.<-
"But we are just friends ..."
Harry: You realize of course that we could never be friends.
Sally: Why not?
Harry: What I'm saying is — and this is not a come-on in any way, shape or form — is that men and women can't be friends because the sex part always gets in the way.
Sally: That's not true. I have a number of men friends and there is no sex involved.
Harry: No you don't.
Sally: Yes I do.
Harry: No you don't.
Sally: Yes I do.
Harry: You only think you do.
Sally: You say I'm having sex with these men without my knowledge?
Harry: No, what I'm saying is they all want to have sex with you.
Sally: They do not.
Harry: Do too.
Sally: They do not.
Harry: Do too.
Sally: How do you know?
Harry: Because no man can be friends with a woman that he finds attractive. He always wants to have sex with her.
Sally: So you're saying that a man can be friends with a woman he finds unattractive?
Harry: No, you pretty much want to nail 'em too.
Sally: What if they don't want to have sex with you?
Harry: Doesn't matter because the sex thing is already out there so the friendship is ultimately doomed and that is the end of the story.