Guest post by "Being Useful" I'd think she's less worried about Irma's lack of presence and more about little Ms. Didjaknowdidja and the legend of Che Gobvera. Sarah's being a tad naive here, so this is the time for explanations and life lessons about what "real" friends are, versus people who are just using you.
At which point Sarah gets to have a good think about what's going on.