From the Wiki for the musical:
The Last Five Years was inspired by Brown’s failed marriage to Theresa O’Neill. O’Neill sued Brown on the grounds that the story of the musical violated non-disparagement and non-disclosure agreements within their divorce decree by representing her relationship with Brown too closely. Brown, in turn, sued O’Neill for interfering with his creative work and his creative process. As part of the legal settlement for both suits, Brown removed all references to the character being Irish Catholic, and changed the song “I Could Be in Love With Someone Like You” to “Shiksa Goddess” in order to reduce the similarity between the character, Cathy, and O’Neill.
Not sure why he’s still allowed to perform it in concert?