Can assault charges get dismissed if the victim left the country?

My friend has recently made a serious error. Til now he has never even gotten a speeding ticket but lost his temper on his wife and caught an Aggravated Assault with a Deadly weapon charge. First there was no bodily injury, and secondly his wife left for her home country. He's currently still in jail but is wondering about any possibility of dismissal if the only actual witness never shows. They are going through a divorce and she has no intention of ever returning to the US. I talk to him often in jail and he's pretty worried that his first and only offense in life is going to land him in prison. Like I said he's a good guy, never even got a traffic ticket, but work stress and other stuff and he made a mistake. He's wondering if there was any chance of dismissal if the witness is not present, much less in country.