Help me out

Well... First That friend who is pulling away one of your Những người bạn is totally wrong for doing that.First Get That person Who IS Mean and look her in the eyes and stand up straight and say something like " Stop It, (Your Những người bạn Name) Is my Friend! That Is Mean What bạn Are Doing!Please Stop it!" then confront her. and tell your friend to ignore that person who is Mean
try to be bởi your friend Alot so that mean person cant get to her. Hope That Helps , Good Luck! :)

If the friend who's being pulled away from bạn didn't do anything wrong, then I would only be Những người bạn with her. If she did, try to get her to apologize to the first one for whatever she did.

First of all, I would pull Friend 1 aside and ask her why she's doing it.
bạn might wanna ask her if anything is going on that bạn might need to talk about.
Then, if she says nothing is going on and that she just doesn't like Friend 2, then I would tell her that true Những người bạn wouldn't be so selfish to keep a friend to themselves.
If she keeps doing it, stop being Những người bạn with Friend 1 and keep bởi Friend 2's side, staying as strong as bạn can for the worst.
Things might get ugly between bạn and Friend 1 if bạn don't keep bởi your friends.
Hope that helps. ^^