The Question and Answer section for David Copperfield is a great resource to ask questions, find answers, and discuss the novel.
Steerforth left Emily in the care of his servant, Littimer, because he was bored with her. Knowing he'd ruined her reputation, Steerforth even advised her to marry Littimer. None-the-less, he no longer cared what she did.
David Copperfield is a lengthy novel, and over the course of the novel he experiences numerous types of losses. What specific chapter does your question pertain to?
Although David mentions that Agnes is perfect many times, he just doesn't seem to have the courage or social intelligence to tell her how he feels.