I've had a few females bust the nest. It usually means they aren't satisfied with the build. They bust it then run away to let the male rebuild the nest better. Only time I've ever had any troubles after a nest bust was first time ever spawning and male killed female. I've learned to be more diligent in watching them since then. Hard and sad lesson learned. But as long as the female has a place to retreat to all is good. She's just not happy with his building skills yet.