
I'm just gonna jump right in here. So even though this film seems like it's supposed to present Gina as the main interest for Marco, I think she is the main thing that maintains Marco's pig face. He is going through survivor's guilt due to his experiences in the war with losing his friends and seeing all the planes ascending to heaven with him in the middle ground. He is scarred. He likes Gina and was the best man at her wedding! But two days later her husband dies and there is nothing that Marco can do but go back down there to face reality. At this point Gina really likes Marco but he feels so undeserving of any love or openness and that manifests itself in his pig face. He feels dirty, yet his morality is so strong that he can't even shoot at Curtiss's plane if it's not the engine. He walks a jagged line. Yet Fio is the one who can really unpack his emotional baggage!
She asks him about his past and makes it come out. She gives him the affection that he can not ask for. As she opens up Marco's emotions she gets a glimpse into his real face and eventually unmasks him completely!
This seems like a strange film for Miyazaki to have done in a way. Mostly just because it's really uncharacteristic. It doesn't deal with the nature/technology tension, nor does it focus on independent children, specifically girls. Fio is more of a sidekick/secondary character to Marco. This time we see an emotionally crippled man in the spotlight. Also, Humphrey Bogart references..? And specifically in 1929 Italy. And directly dialoguing with fascism. Again.. why? I don't know. But to focus on a pilot makes sense because Miyazaki probably wanted an outlet for his more than interest in planes and aviation to flourish. All of his films have been pretty much leading up to directly dealing with planes.