OpenPaths, the app used to gather data for this group, only logs what it determines as "significant" changes in users' locations, which leads to some variablity in the representations of data. You can see this by watching Roommate 2 and 3's trails. These two spent the most time together, and often shared similar paths, but you'll see that the circles representing them rarely move in perfect unison (though they are often very close to one another).
The interesting thing about this group was the degree to which their data couldn't capture the reality of what they were experiencing. I was present for the goodbye their data leads up to, and I witnessed every bit of its difficulty. But data visualizations add a level of abstraction over real world events; they gather the messiness of human life and render it in objective simplicity. In life, goodbyes can be heartbreaking affairs, painful for all involved.
But on a map, a goodbye is as simple as one dot moving out of view.