Etienne is waiting for Marie-Laure to return from the bakery. He always times her trips to and from the shop, and this trip has taken twice as long as usual—and Marie-Laure isn’t even back yet. Etienne looks out of the window, but can’t see anything. His mind rushes to the worst conclusions—she could have been captured, or the bakery could be in flames.
In this section—which follows Etienne’s perspective, for once—we see the extent of his paranoia. Etienne’s mind always jumps to the worst conclusion, not only because of his phobia and possible PTSD, but also because he loves Marie-Laure so desperately.
Etienne tries to leave his house to look for Marie-Laure. As he goes to the door, his heart beats quickly, and he develops a headache. Nonetheless, he opens the door, walks to the gate, and goes outside.
Here we recognize Etienne’s bravery in the same instant that we recognize the extent of his problem. It is a hugely courageous act for Etienne to go outside, and he is only able to find the strength to do so because of his love for Marie-Laure.