I can't find the edit button to edit my last post. It's probably right in front of me. Anyway...
I was wrong about Zoe mentioning her friends Kat and (forgot his name already) in her journal. It's actually when she's thinking about what to say to Ada that she mentions how she would like to go back to the university someday and see them. The way she phrased it, it sounded like she hadn't contacted them at all yet. They might be gone too.