Boot camp stuck on "Status: Partitioning disk..."

You have chosen the Windows size to be very close to the available Free Space. This can be very slow when trying to create contiguous disk space for the Windows partition. The best way to get this size to work, is by using a Time Machine backup/erase the internal disk/restore before you partition. The Restore will make the underlying disk have contiguous disk space.

Before you abort the partitioning process, start a Terminal window from Application -> Utilities and post the output of

diskutil list

diskutil cs list

This would show us the current state. You can then decide whether to abort the process or not.