The souls created as unified male and female. They are separated before they come down to the world and placed where they need to be for their correction process.
The unification of the souls on the lower level is difficult because it depends on the upper levels. The souls in their bodies try to connect to each other buy they are strongly influenced by the physical level. When he soul are ‘dressed’ in a body, they can only use their physical eyes, unable to see their true soul mate.
The great advantage of living and build life and family with a soul mate is that they both complement each other on their correction process.
The splitting of the Red Sea required actions on spiritual and physical levels. A proper action below needed to activate the force above to animate the process and manifest it below.
The splitting of the Sea was difficult because God needed to use one force to open the sea and save the Israelites and another force to drown the Egyptians. These opposite forces go against the normal flow of nature and cause difficulties.