Here's the deal. A ski is basically a polymer-based composite. The resin that holds the whole thing together is cured during the manufacturing process to a certain level of hardness, but it still remains resilient. After leaving the factory, the resin continues to cure, very slowly when cold, much faster during summer storage. That's why you're advised to store skis and cold and dark places. Light also accelerates the curing process (ever had a dentist use the UV light to cure your filling?). After a few years, it becomes much more brittle, regardless of how much use it had.
I'm guessing this ski is at least 5 years old. The impact that caused this damage might have caused just a nick on a new ski.
So far, the damage looks superficial. I would probably dab some marine epoxy and try to glue it together. It might hold, and your GF may get another season or two out of them. But if a second issue like this came up, I'd be inclined to toss them. If a ski is prone to disintegrate under my feet, I don't want to be on it.