A story may explain a reason directly or give a clue through an action. Choose the reason supported by the words rather than inventing an extra event. An inference is an evidence-based idea, not a certainty about every hidden thought.
Worked example
If Ada moves a book away from spilled water, protecting the book is a supported reason. The text does not show that she dislikes reading.
Original fiction: The Wet Table
Nina placed her drawing on the table. Eli knocked over a cup of water. Nina lifted the drawing before the water reached it. Eli brought a towel and dried the table. "That was close," Nina said. She put the drawing back only after the table was dry.