It is perfectly natural to look at your best friend like that. Unnecessary physical contact is also wholly unremarkable. (Just kiss already, you guys).
Deryn Sharp, who cross-dresses as a boy to join the Air Service, and her friend
Aleksandar Ferdinand, the fictional son of Archduke Franz Ferdinand of Austria, from Scott Westerfeld's delightful WWI AU series, Leviathan. You should totally read it, and this is why
With thanks to Kate Beaton and apologies to everybody else. More serious titles were not forthcoming. The character designs, etc, heavily inspired by Keith Thompson's illustrations.