Why does my mac no longer support Windows 8?

So, about 2 years ago, I used BootCamp to partition my macbook (13-in mid-2010). I had Windows 8 installed on the partition, and it was working fine. I upgraded to Windows 8.1 and began experiencing problems, so I decided to start over with Windows 8. The only problem is that when I closed out that partition and started a new one, BootCamp informed me that my mac only supports Windows 7, despite having had Windows 8 installed on there just hours before. What happened to make my mac stop supporting 8, and how can I fix this?