Too many people haven't done any research and don't have a clue what they're talking about when it comes to Ben and his legal troubles.
Simply put, he wasn't charged because there's not anywhere near enough evidence. I'm not going to go over all the various facts, but here's a few key points:
1. Her various accounts and those of her friends have key significant details at odds with each other. For example, one of her friends claims that she was "dragged" down the hallway, while her account makes no mention of this. Many of their statements directly contradict the original report she gave police.
2. She claimed she didn't know if she had intercourse, then said she didn't and then said she did.
3. There is no DNA evidence, which is virtually impossible if intercourse took place.
4. Those in Ben's party, including police officers, have said they didn't notice anything out of the ordinary.
It's simply a he said/she said story where the vast majority of the physical evidence is on the he said side.
Furthermore, the DA said he did not have probable cause, which is necessary to charge a person with a crime. Probable cause is defined as "a reasonable belief that a person has committed a crime". Please note this is a much lower standard than the one to convict, which is beyond a reasonable doubt. Now if the DA - someone who had access to more facts than ANY of us - says that there is not a reasonable belief that Ben committed a crime, when why would you?
Sure, if you want to be angry that he put himself in this position, that's reasonable. But calling him a rapist and the other garbage I'm reading? If you're posting that, know that the DA himself thinks you're wrong.