How did I miss it!

One of my correspondents pointed out to me that the London Handel Festival production of Handel's Alessandro at the Britten Theatre, was intended to all be Alessandro's dream. During the overture he has an argument with his boyfriend, hits his head and then dreams the opera where he has become butch and heterosexual. I must confess that I missed all this and took the opening and closing tableau to be pointless flash-backs, meant to indicate that Alessandro was bisexual (like the real Alexander). I'm not sure that understanding this mis en scene would have helped me enjoy the opera more, probably not; in fact I rather think it might have annoyed me even more.