story: Rowan went into his backyard to play with his dog Harper. They usually play well together, but today was different. Every time Rowan threw the ball to Harper, Harper would not catch. Then Rowan realized Harper was very sleepy. They both decided to go back inside and have a nap instead.
 selected sentence: Then Rowan realized Harper was very sleepy.
Rowan realizes Harper is very sleepy >Causes/Enables> Rowan stops playing fetch