Having just seen the film (and never having read the book), I wonder why the reviewer considers the early parts of the film "boring"? The film starts as a psychological story of a damaged character, then becomes a thriller which explores the damage done. Emily Blunt (and the rest of the cast) deliver great performances in their roles, with each character being not sympathetic and highly complex.

We like watching Emily Blunt sulk in anything she wants to...

This is not a good movie and is predictable about halfway through. If you like seeing someone be confused in an alcoholic haze for 90 minutes go, for me it got boring about 15 minutes in.