Sora's way to avoid thinking of her future is to throw herself into the moment and constantly be distracting herself. Tsukiko's way to avoid thinking of her future is to lock herself in her room and avoid exposure to the outside world. Interesting how opposite that is.
Sora doesn't want to think about her complicated family life, so instead she makes sure that she spends as much time as possible doing something intensive with Tsukiko... that's her happy place after all.
What those two need to realize is that if they share the cognitive load and emotional charge of any individual situation with each other, most situations become manageable. Unless it's something that affects both of them strongly at the same time, then they're effed -- but given how different they are, the odds of such a situation are negligible.