Revealing mistake: When Kate kisses Morgan in front of 1620 N. Racine, the camera moves up through the branches of a tree. You can see one of the lower branches shake when it is bumped by the crane. (01:17:20)
Revealing mistake: Kate's birthday is July 10th. When she is (with long hair) outside on the patio with Alex, you can see their breath as they talk, and there is not a living thing in the back yard, it's all dormant (as in late fall/winter).
Answer: The movie is not about them trying to find ways to meet. They are not trying that hard to meet and the time distance is a metaphor. I think the movie misses the tension that she is trepidatious about meeting and he is trying to respect that. He gets killed the first time for trying to force it! This shows when the stack of letters is piling away. She is worried he is a coward who will not be able to handle real romance. This is shown in his retreat to build mass produced houses and has something to do with his mom/dad. She's the doctor, he's the architect: she saves people for a living and is hung up about her own father's death. It's only when it's life or death that she gets over it and he also figures himself out and stops trying to fix everything.