Why did n't you care ? After sunset , riding home on our bicycles , I made you stay in the grass . The light - oh , a barely dim force - could not help you then . And the road was a far darker gray than you thought .

Question: Why is the biking abilities of the subject impaired ?
Answer: They only know how to bike on the grass .The narrator is hurting them .It is dark out .They ca n't bike well .