Has she had kids before??? She looks maybe a little swelled back there but I don't see clumpy hair on the tail. I would for sure keep her with the buck she might be getting ready to come into heat. I would actually keep him with her for 2 months to be on the safe side.....even 3 I don't see anything wrong with.
It does look like there's been some action by the poofiness.
You should see some dried semen though.
Many times I have brought does in who were not in heat who stayed for a few weeks & 5 mos later voila!