"I'm not in love with him. I'm in love with ghosts."
Hana says this to David when he says that she is in love with Laszlo. It tells us that everyone she has loved has been taken by the war. That they are dead and she cannot stop loving them.
" 'Yes' is a comfort, 'absolutely' is not."
Katharine says this to Laszlo while in the truck during the sandstorm. She's asked him if everything is going to be alright and when he changes from saying yes to absolutely it means that there is something wrong, and it concerns her greatly that things are in fact not alright.
"Of course you idiot I always wear it. I've always worn it. I've always loved you."
Katharine says this to Laszlo after she is badly injured after Geoffrey crashes the plane. The thimble is a symbol that she has been commited to him though he believes that she cares nothing for him and has discarded him like a piece of garbage.