Weeks later, the aftermath of the shooting continued to weigh on the detective. Upon her return to work, Rollins was mandated to see a therapist.

Despite claims that she was over it, Rollins’ behavior in Episode 3 — “Mirror Effect” — said differently. After her daughters complained of a “monster” hiding in the closet, Rollins went all Die Hard, terrifying her small children in the process. It wasn’t long before her boyfriend, Carisi (played by Peter Scanavino), and Captain Benson (Mariska Hargitay) expressed their concern.

Source: https://www.distractify.com/p/why-is-rollins-in-therapy-svu