Need Advice about unfair work promotion?

I am writing this in regards to my girlfriend. She works at a inbound pharmacutical company. It is very diverse there the majority are black. My girlfriend is white by the way. She has been there for three years. Working her butt off gets compliments all the time, stays overtime, follows procedures and trains all new employees. Well today she came home crying hystraically. What happened was there was. She is a manager there. There was a position that opened up for anyone who wanted to interview she was interested yet the manager in that divison she knows and is very hard to work for so she decided not to put her self in for that positon. This employee who for my girlfriend who is not yet at her level interviewed for the position. It really was ackward any my gf didnt understand how she was eligible since she is new and hasnt reached a manager level yet. It ended up they interviewed her and told her that they think she needs more experience so they moved my girlfreinds boss who is a considered "lead level" into that position leaving an opening for that "lead" position. My girlfriend was next in line since she has been with the company the longest to move into that :lead" role. It ends up by default the girl who works for my girlfriend that asked her to be in that role and she excepted it. From what I have been told this girl is unexperienced is no where near the level of exeperience that my girlfreind is at yet they moved her there. It was a slap in my gf face. Everyone at work came up to her and was shocked and asked why they didnt move her. They never said anything to my girl. They even went as far as writing an email (which they never do) to everyone in the company congratualting her and had a paragraph how great she is. I am not raciest but both are black and I feel this has something to do with it since we cant think of anyother reason. Does anyone have any suggestions what she should do? She is really upset and now she has to work closely with this girl who is now her boss...