Honestly? I'd tell her she wasn't welcome since it is all too clear that she is not enjoying herself AND she is ruining the situation for the rest of you.
And she can grow up and suck it up.
Coddling people like this serves no purpose. And I also imagine it is the way she does concerning everything else in her life.
Her behavior will end up getting one of the rest of you hurt.
Life isn't fair, it isn't pretty, and no one wants to put up with someone whining nonstop.
Being firm with her might be the best thing that ever happened to her.
But no way would she be going out with me anymore.