Walter and Skyler were about to get divorced. But Skyler being calculating and manipulative knew that without money she would not be able to survive, so reconciled with Walter. He happily obliged in spite of Skyler's previous humiliation and coldness towards him.
Walter could have had better chances of success of providing for his family being away from the present city and restarting his business someplace else as a complete unknown personality (with or without Gus).
In this way,
Hank would have never caught hold of the book which Gale had presented to Walter.
Does this show that Walter was weak minded in spite of being smart and his poor choices got to him again here?