Santiago's life was already tottering presumably from his break up with Luis. We see him returning home after a debauched night to the daughter he had carelessly locked indoors causing her to miss an important engagement. Resentful at first, we see that fundamentally they have a good relationship as they chase each other round the room.
The relationship with mum the bolter is more fractious for both daughter and ex husband. A visit to her in Brazil seems to break the relationship completely.
Santiago seeks to go backwards to the comfort of his previous lives but others have moved on. Instead of knuckling down, he spirals deeper into self-destructive actions. Drink, drugs and indiscriminate sex with guys he just met become his panacea to escape what he feels is a terrible life. Except his life is a good one. He has a job he loves, earns money, has a lovely daughter, inspires loyalty in his employees, has friends. But it's not enough; he's on the hunt for more.
It's clear that there needs to be a make or break point. It comes near the end of the film when Laila embarks to Montreal. He was frightened of her going but it represents new freedoms and opportunities for both of them.
I watched the whole hour and fifty minutes of this film without looking once at the time. It had me hooked from beginning to end. I really do recommend it.