It is not very clear but
It became to to hard to govern
Then there was a war when they tried to divide Rome to make it easy to handle.
But when taxes and prices went up people started to move out of Rome and the population grew smaller and smaller.The poor struggled alot and the rich grew disinterested in helping Rome
The Roman Empire fell apart because the Western empire grew to great that the Western European Roman empire was attacked by barbarian tribes in Europe
