This could happen, e.g. if Obsessive Inmate is already committed to a story alone when the Binding Worm enters play.
Here's the Binding Worm's card text: Characters cannot commit to stories alone.
Does this affect a committed character in any way?
And how does it interact with card effects that force characters to commit, e.g. using Y'Golonac's ability? Would the Binding Worm force the player to commit a second character to accompany the one targeted by Y'Golonac's ability?