Why can't I partition my SSD and install Win7 through BootCamp?

Question

boot camp

So we have

I want to install Win7 x86 as a parallel system, but I can't partition the hard drive into sections - both Boot Camp and Disk Utility give an error. I tried to restore the hard drive through the native macOS utility and rebooted with cmd + r pressed - as a result, all problems were fixed and are no longer found through the disk utility, but the disk is still not partitioned.
Third-party tools and alternatives to bootcamp did not help either (for example, this rutracker.org/forum/viewtopic.php?t=4358810 ), nothing works.
The flash drive created by the bootcamp also does not allow splitting the disk on which macOS is installed and does not detect an external usb HDD.
I see two outputs:
1. Make a backup copy of the system through Time Machine, completely format the disk and restore the system from the backup. And then try your luck and again try to divide the hard one into two sections and install Windows with standard tools.
- what may be needed for this - a MacOS bootable USB flash drive? How to do a full disk format? What is the success rate of this method?
2. From a computer on Windows, put Windows on an external USB HDD, connect it to a macbook and then install the drivers created by the bootcamp.
- As a result, we will get a very slow Windows (usb 2.0), but this is also an extreme option. What is the chance of success in this case? how can this be done, in addition to what is described here skesov.ru/kak-sdelat-portable-versiyu-windows-na-v...? Will it boot from the Macbook later.
3. Your option

Answer 1

If I'm not mistaken, since OS X version 10.0.x... not just disk partitioning, but using CoreStorage, which in turn can impose restrictions. And yes, check if you have volume encryption enabled... With this option, it is not possible to partition the disk.