When I listen to this song I feel that it describes how knowing someone very well gradually encroaches into your own life.
It's almost as though the singer
feels like they have known the listener for a long time, so long, that the listener does not recognise the singer any more. 'you don't remember me'
The singer tries to forget how good the listener was before, but it comes back in their dreams. 'dream I do'. This is also supported in the second verse.
The listener has become the singer's whole life 'I'll give up everything.' and ' So many things inside that are just like you are taking over'