The Big Picture (L'homme qui voulait vivre sa vie)

I’ve got this problem with the Big Picture. The acting is fine, there are some good performances, and it has Catherine Deneuve in it. The photography is almost sublime in places, moody clouds, beautiful seascapes, great scenery. The music is not intrusive; it engages you without leading you by the nose. I just find the plot on the whole rather far fetched.
It’s a story of what is never presented as the perfect French family. The mother, Sarah, and father, Paul, don’t get along, their youngest child is incredibly unhappy. Anyway Paul suspects Sarah of having an affair; he gets drunk at a dinner party and insults his wife and child in front of all their friends. Push comes to shove, she asks for a divorce. By now he’s worked out who she’s having the affair with and confronts him.
What could have a been a drama of manners, of people making sensible life changing choices descends into a film about changing identities and blowing things up. I refuse to believe that just because Paul cannot see the big picture that he would act in such a ludicrous and unbelievably ridiculous manner. Unless that is I’m missing something entirely that is. French thrillers used to be renowned for their subtlety; they probably still are in the main, but not this one. The title in French translates as the man who wanted to live his life. Honestly.