Spoilers needed

1.) What was the end about?
2.) What did it mean?
3.) I kept thinking Noah was a delusion that Emily was having, I know he was real, but this movie was different...any thoughts ...can someone explain the movie to me.
4.) I am a nurse, I get the whole schizo thing, but, I do not believe there is a such dx , but I have not done the research.

I think there were undercurrents that obsessive love can lead to deadly circumstances, anyone else?