The Judge of the case was going to accept a plea bargain but backed out on the deal and that is what caused Roman to flee the United States, and as stated by others before, the woman herself wishes the charges were dropped.
Some of you fail to see the seriousness behind fleeing your sentence. Even if the girl wanted the charges dropped, it still leaves open the fact that Polanski fled the country to avoid his sentence. That in itself is punishable.