That's why I just use a VM, I skip all the complications of having to fix bootloaders and broken installs. If anything goes wrong with windows I just delete the VM. Arch barely uses any RAM, so even back when I had only 8GB, windows ran incredibly well. I've updated to 16GB (because I needed the 64 bit version of excel and I wasn't being able to install it due to RAM requirements). Ever since then, I don't even look back to dual booting.
Funny story, originally my laptop was dual booted, but I removed windows completely and formated the partition, and since it was at the beggining of the drive, and you cannot move blocks around so easily in storage (I needed another SSD or hard drive to copy them momentarily) I was left with a hole in my storage. What I did was, mount the directory with the VM image storage to the empty partition. So now it's kind of "dual booting" with some extra steps and with the added benefit of being able to use both OS' at the same time
[TL;DR] If possible, just use a VM
I had no idea mageia existed until I met a dude who had it