Prerequisites: Max out Cassandra's level 2 friendship
Reward: None
Unlocks: Cassandra level 3 friendship
Continue to speak to Cassandra after your first encounter and it'll quickly become clear that she's still worried about her anxiety levels. You'll need to befriend her more to see if you can resolve her problems. Cassandra works at the Willow Waters Bathhouse, and most frequently shows up there during the day. The rest of the time she can be a bit difficult to find, though she does seem to appear around her husband Osman on a fairly regularly basis. Your dog, as ever, will help track Cassandra down.
Once you've boosted the second level of your friendship with Cassandra to the max her coworker, Olive, will post a notice on the Bulletin Boards throughout Moonbury. She wants to speak to you in private at the Willow Waters Bathhouse, from 9:00 to 18:00, any day of the week. She's worried about Cassandra's behavior of late, and wonders if something's going on between Cassandra and Osman.
Not wanting to get too involved, Olive passes the responsibility of speaking to Osman off to you. Thanks. Osman is a little elusive compared to the average townsperson, though you're most likely to find him behind his desk at the Police Department to the south of your house. The resulting conversation forces you to diagnose Cassandra, and what follows resolves her issues. Kinda. Your relationship with her will jump to the third level, ending the quest.