FUCK...don't be such a bunch of drama queens, this is no big deal. If you take a lot of big dicks in the ass, it's going to happen sometimes. It does not mean her ass is wrecked for life, though that certainly can happen after a long career of getting stretched by abnormally large cocks. Taking the average sized dick in the shitter once in a while is NOT going to make a girl **** her drawers. If you do anal fucking right there's nothing wrong with it.
By the way, there's a whole thread on this board devoted to prolapses. So there.