[souffle]

I think both look to be female too. The others are right in that the little one is likely being bullied and not getting enough food. The stress of being bullied can also make them lose weight. They will probably thrive better alone. I'd move the little one to a totally new. clean cage so she doesn't think the cagemate is lurking round the corner. It's usually the bully who sulks the most but they should both settle alone in around 10 days.