The book starts off normally. The protagonist is a young man. The protagonist eventually starts and/or watches a fire in a rich neighborhood in California.
The protagonist eventually meets up with some girl. They end up in space and the girl tries to sabotage something.
It turns out that the protagonist and the girl were both in dream machines of some sort at a clinic. They are addicted to dreaming in those machines. I think one of them leaves at the end.
I don't know the title or the author. I read it in the 90s.