Keeping the players happy with one another is one of the jobs of the DM, in my experience (both as player and DM).

First of all, how many players are unhappy? If it's just you, you're stuffed. If not, you have something to work with. However, in gauging this, don't let yourself put together a gang vs annoyingplayer - watch during the game for signs of annoyance, rather than having a backbiting session. It's less satisfying, but easier in the long run.

I would have a word with the DM - not putting in a complaint, but asking how they feel the game is hanging together and if they're happy with the dynamics, then put forward your experience. If the DM can't keep you all playing together happily, then you have to cut your losses and move on.

All of this is very general advice, though, because I feel I am missing a good grasp of exactly how and why she's annoying - how has she ended up wrecking the democracy? Is she going off in her own direction, or just making comments? Has she played before, or is this her first time?

When the wizard came into the picture, we were desperate for help, of any kind, and my bf's character had history with them
This is ambiguous. I really don't get what you mean here at all.